[ZOOKEEPER-4672] Code cleanup - apply JDK7 Diamond operator consistently (#1979)

Co-authored-by: Moderne <team@moderne.io>

zookeeper-jute/src/main/java/org/apache/jute/RecordWriter.java

@@ -32,7 +32,7 @@ public class RecordWriter {
     private OutputArchive archive;
 
     static HashMap<String, Method> constructFactory() {
-        HashMap<String, Method> factory = new HashMap<String, Method>();
+        HashMap<String, Method> factory = new HashMap<>();
 
         try {
             factory.put(

zookeeper-jute/src/main/java/org/apache/jute/compiler/JRecord.java

@@ -143,7 +143,7 @@ public class JRecord extends JCompType {
         return "    a_.WriteRecord(" + fname + ",\"" + tag + "\");\n";
     }
 
-    static Map<String, String> vectorStructs = new HashMap<String, String>();
+    static Map<String, String> vectorStructs = new HashMap<>();
 
     public void genCCode(FileWriter h, FileWriter c) throws IOException {
         for (JField f : mFields) {

zookeeper-server/src/main/java/org/apache/zookeeper/ClientCnxn.java

@@ -140,7 +140,7 @@ public class ClientCnxn {
 
     }
 
-    private final CopyOnWriteArraySet<AuthData> authInfo = new CopyOnWriteArraySet<AuthData>();
+    private final CopyOnWriteArraySet<AuthData> authInfo = new CopyOnWriteArraySet<>();
 
     /**
      * These are the packets that have been sent and are waiting for a response.
@@ -150,7 +150,7 @@ public class ClientCnxn {
     /**
      * These are the packets that need to be sent.
      */
-    private final LinkedBlockingDeque<Packet> outgoingQueue = new LinkedBlockingDeque<Packet>();
+    private final LinkedBlockingDeque<Packet> outgoingQueue = new LinkedBlockingDeque<>();
 
     private int connectTimeout;
 
@@ -465,7 +465,7 @@ public class ClientCnxn {
 
     class EventThread extends ZooKeeperThread {
 
-        private final LinkedBlockingQueue<Object> waitingEvents = new LinkedBlockingQueue<Object>();
+        private final LinkedBlockingQueue<Object> waitingEvents = new LinkedBlockingQueue<>();
 
         /** This is really the queued session state until the event
          * thread actually processes the event and hands it to the watcher.
@@ -1019,11 +1019,11 @@ public class ClientCnxn {
 
                     while (dataWatchesIter.hasNext() || existWatchesIter.hasNext() || childWatchesIter.hasNext()
                             || persistentWatchesIter.hasNext() || persistentRecursiveWatchesIter.hasNext()) {
-                        List<String> dataWatchesBatch = new ArrayList<String>();
-                        List<String> existWatchesBatch = new ArrayList<String>();
-                        List<String> childWatchesBatch = new ArrayList<String>();
-                        List<String> persistentWatchesBatch = new ArrayList<String>();
-                        List<String> persistentRecursiveWatchesBatch = new ArrayList<String>();
+                        List<String> dataWatchesBatch = new ArrayList<>();
+                        List<String> existWatchesBatch = new ArrayList<>();
+                        List<String> childWatchesBatch = new ArrayList<>();
+                        List<String> persistentWatchesBatch = new ArrayList<>();
+                        List<String> persistentRecursiveWatchesBatch = new ArrayList<>();
                         int batchLength = 0;
 
                         // Note, we may exceed our max length by a bit when we add the last

zookeeper-server/src/main/java/org/apache/zookeeper/Environment.java

@@ -59,7 +59,7 @@ public class Environment {
     }
 
     public static List<Entry> list() {
-        List<Entry> l = new ArrayList<Entry>();
+        List<Entry> l = new ArrayList<>();
         put(l, "zookeeper.version", Version.getFullVersion());
 
         try {

zookeeper-server/src/main/java/org/apache/zookeeper/KeeperException.java

@@ -417,7 +417,7 @@ public abstract class KeeperException extends Exception {
          */
         THROTTLEDOP (-127);
 
-        private static final Map<Integer, Code> lookup = new HashMap<Integer, Code>();
+        private static final Map<Integer, Code> lookup = new HashMap<>();
 
         static {
             for (Code c : EnumSet.allOf(Code.class)) {

zookeeper-server/src/main/java/org/apache/zookeeper/MultiOperationRecord.java

@@ -43,7 +43,7 @@ import org.apache.zookeeper.proto.SetDataRequest;
  */
 public class MultiOperationRecord implements Record, Iterable<Op> {
 
-    private List<Op> ops = new ArrayList<Op>();
+    private List<Op> ops = new ArrayList<>();
     private Op.OpKind opKind = null;
 
     public MultiOperationRecord() {

zookeeper-server/src/main/java/org/apache/zookeeper/MultiResponse.java

@@ -41,7 +41,7 @@ import org.apache.zookeeper.proto.SetDataResponse;
  */
 public class MultiResponse implements Record, Iterable<OpResult> {
 
-    private List<OpResult> results = new ArrayList<OpResult>();
+    private List<OpResult> results = new ArrayList<>();
 
     public void add(OpResult x) {
         results.add(x);
@@ -101,7 +101,7 @@ public class MultiResponse implements Record, Iterable<OpResult> {
 
     @Override
     public void deserialize(InputArchive archive, String tag) throws IOException {
-        results = new ArrayList<OpResult>();
+        results = new ArrayList<>();
 
         archive.startRecord(tag);
         MultiHeader h = new MultiHeader();

zookeeper-server/src/main/java/org/apache/zookeeper/Transaction.java

@@ -34,7 +34,7 @@ import org.apache.zookeeper.data.ACL;
 public class Transaction {
 
     private ZooKeeper zk;
-    private List<Op> ops = new ArrayList<Op>();
+    private List<Op> ops = new ArrayList<>();
 
     protected Transaction(ZooKeeper zk) {
         this.zk = zk;

zookeeper-server/src/main/java/org/apache/zookeeper/ZKUtil.java

@@ -40,7 +40,7 @@ import org.slf4j.LoggerFactory;
 public class ZKUtil {
 
     private static final Logger LOG = LoggerFactory.getLogger(ZKUtil.class);
-    private static final Map<Integer, String> permCache = new ConcurrentHashMap<Integer, String>();
+    private static final Map<Integer, String> permCache = new ConcurrentHashMap<>();
     /**
      * Recursively delete the node with the given path.
      * <p>
@@ -202,7 +202,7 @@ public class ZKUtil {
         ZooKeeper zk,
         final String pathRoot) throws KeeperException, InterruptedException {
         Queue<String> queue = new ArrayDeque<>();
-        List<String> tree = new ArrayList<String>();
+        List<String> tree = new ArrayList<>();
         queue.add(pathRoot);
         tree.add(pathRoot);
         while (!queue.isEmpty()) {
@@ -307,4 +307,4 @@ public class ZKUtil {
         }
         return sb.toString();
     }
-}
+}

zookeeper-server/src/main/java/org/apache/zookeeper/ZooDefs.java

@@ -138,19 +138,19 @@ public class ZooDefs {
          * This is a completely open ACL .
          */
         @SuppressFBWarnings(value = "MS_MUTABLE_COLLECTION", justification = "Cannot break API")
-        ArrayList<ACL> OPEN_ACL_UNSAFE = new ArrayList<ACL>(Collections.singletonList(new ACL(Perms.ALL, ANYONE_ID_UNSAFE)));
+        ArrayList<ACL> OPEN_ACL_UNSAFE = new ArrayList<>(Collections.singletonList(new ACL(Perms.ALL, ANYONE_ID_UNSAFE)));
 
         /**
          * This ACL gives the creators authentication id's all permissions.
          */
         @SuppressFBWarnings(value = "MS_MUTABLE_COLLECTION", justification = "Cannot break API")
-        ArrayList<ACL> CREATOR_ALL_ACL = new ArrayList<ACL>(Collections.singletonList(new ACL(Perms.ALL, AUTH_IDS)));
+        ArrayList<ACL> CREATOR_ALL_ACL = new ArrayList<>(Collections.singletonList(new ACL(Perms.ALL, AUTH_IDS)));
 
         /**
          * This ACL gives the world the ability to read.
          */
         @SuppressFBWarnings(value = "MS_MUTABLE_COLLECTION", justification = "Cannot break API")
-        ArrayList<ACL> READ_ACL_UNSAFE = new ArrayList<ACL>(Collections.singletonList(new ACL(Perms.READ, ANYONE_ID_UNSAFE)));
+        ArrayList<ACL> READ_ACL_UNSAFE = new ArrayList<>(Collections.singletonList(new ACL(Perms.READ, ANYONE_ID_UNSAFE)));
 
     }
 

zookeeper-server/src/main/java/org/apache/zookeeper/ZooKeeper.java

@@ -285,7 +285,7 @@ public class ZooKeeper implements AutoCloseable {
                 synchronized (watches) {
                     Set<Watcher> watchers = watches.get(clientPath);
                     if (watchers == null) {
-                        watchers = new HashSet<Watcher>();
+                        watchers = new HashSet<>();
                         watches.put(clientPath, watchers);
                     }
                     watchers.add(watcher);
@@ -1665,7 +1665,7 @@ public class ZooKeeper implements AutoCloseable {
     }
 
     private List<OpResult> validatePath(Iterable<Op> ops) {
-        List<OpResult> results = new ArrayList<OpResult>();
+        List<OpResult> results = new ArrayList<>();
         boolean error = false;
         for (Op op : ops) {
             try {
@@ -1694,7 +1694,7 @@ public class ZooKeeper implements AutoCloseable {
 
     private MultiOperationRecord generateMultiTransaction(Iterable<Op> ops) {
         // reconstructing transaction with the chroot prefix
-        List<Op> transaction = new ArrayList<Op>();
+        List<Op> transaction = new ArrayList<>();
         for (Op op : ops) {
             transaction.add(withRootPrefix(op));
         }

zookeeper-server/src/main/java/org/apache/zookeeper/ZooKeeperMain.java

@@ -59,11 +59,11 @@ import org.slf4j.LoggerFactory;
 public class ZooKeeperMain {
 
     private static final Logger LOG = LoggerFactory.getLogger(ZooKeeperMain.class);
-    static final Map<String, String> commandMap = new HashMap<String, String>();
-    static final Map<String, CliCommand> commandMapCli = new HashMap<String, CliCommand>();
+    static final Map<String, String> commandMap = new HashMap<>();
+    static final Map<String, CliCommand> commandMapCli = new HashMap<>();
 
     protected MyCommandOptions cl = new MyCommandOptions();
-    protected HashMap<Integer, String> history = new HashMap<Integer, String>();
+    protected HashMap<Integer, String> history = new HashMap<>();
     protected int commandCount = 0;
     protected boolean printWatches = true;
     protected int exitCode = ExitCode.EXECUTION_FINISHED.getValue();
@@ -95,7 +95,7 @@ public class ZooKeeperMain {
 
     static void usage() {
         System.err.println("ZooKeeper -server host:port -client-configuration properties-file cmd args");
-        List<String> cmdList = new ArrayList<String>(commandMap.keySet());
+        List<String> cmdList = new ArrayList<>(commandMap.keySet());
         Collections.sort(cmdList);
         for (String cmd : cmdList) {
             System.err.println("\t" + cmd + " " + commandMap.get(cmd));
@@ -126,7 +126,7 @@ public class ZooKeeperMain {
      */
     static class MyCommandOptions {
 
-        private Map<String, String> options = new HashMap<String, String>();
+        private Map<String, String> options = new HashMap<>();
         private List<String> cmdArgs = null;
         private String command = null;
         public static final Pattern ARGS_PATTERN = Pattern.compile("\\s*([^\"\']\\S*|\"[^\"]*\"|'[^']*')\\s*");
@@ -188,7 +188,7 @@ public class ZooKeeperMain {
 
                 if (!opt.startsWith("-")) {
                     command = opt;
-                    cmdArgs = new ArrayList<String>();
+                    cmdArgs = new ArrayList<>();
                     cmdArgs.add(command);
                     while (it.hasNext()) {
                         cmdArgs.add(it.next());
@@ -207,7 +207,7 @@ public class ZooKeeperMain {
         public boolean parseCommand(String cmdstring) {
             Matcher matcher = ARGS_PATTERN.matcher(cmdstring);
 
-            List<String> args = new LinkedList<String>();
+            List<String> args = new LinkedList<>();
             while (matcher.find()) {
                 String value = matcher.group(1);
                 if (QUOTED_PATTERN.matcher(value).matches()) {
@@ -237,7 +237,7 @@ public class ZooKeeperMain {
     }
 
     public static List<String> getCommands() {
-        List<String> cmdList = new ArrayList<String>(commandMap.keySet());
+        List<String> cmdList = new ArrayList<>(commandMap.keySet());
         Collections.sort(cmdList);
         return cmdList;
     }

zookeeper-server/src/main/java/org/apache/zookeeper/cli/AclParser.java

@@ -37,7 +37,7 @@ public class AclParser {
     public static List<ACL> parse(String aclString) {
         List<ACL> acl;
         String[] acls = aclString.split(",");
-        acl = new ArrayList<ACL>();
+        acl = new ArrayList<>();
         for (String a : acls) {
             int firstColon = a.indexOf(':');
             int lastColon = a.lastIndexOf(':');

zookeeper-server/src/main/java/org/apache/zookeeper/client/ConnectStringParser.java

@@ -41,7 +41,7 @@ public final class ConnectStringParser {
 
     private final String chrootPath;
 
-    private final ArrayList<InetSocketAddress> serverAddresses = new ArrayList<InetSocketAddress>();
+    private final ArrayList<InetSocketAddress> serverAddresses = new ArrayList<>();
 
     /**
      * Parse host and port by spliting client connectString

zookeeper-server/src/main/java/org/apache/zookeeper/client/StaticHostProvider.java

@@ -50,7 +50,7 @@ public final class StaticHostProvider implements HostProvider {
 
     private static final Logger LOG = LoggerFactory.getLogger(StaticHostProvider.class);
 
-    private List<InetSocketAddress> serverAddresses = new ArrayList<InetSocketAddress>(5);
+    private List<InetSocketAddress> serverAddresses = new ArrayList<>(5);
 
     private Random sourceOfRandomness;
     private int lastIndex = -1;
@@ -62,9 +62,9 @@ public final class StaticHostProvider implements HostProvider {
      */
     private boolean reconfigMode = false;
 
-    private final List<InetSocketAddress> oldServers = new ArrayList<InetSocketAddress>(5);
+    private final List<InetSocketAddress> oldServers = new ArrayList<>(5);
 
-    private final List<InetSocketAddress> newServers = new ArrayList<InetSocketAddress>(5);
+    private final List<InetSocketAddress> newServers = new ArrayList<>(5);
 
     private int currentIndexOld = -1;
     private int currentIndexNew = -1;

zookeeper-server/src/main/java/org/apache/zookeeper/common/StringUtils.java

@@ -34,7 +34,7 @@ public class StringUtils {
      */
     public static List<String> split(String value, String separator) {
         String[] splits = value.split(separator);
-        List<String> results = new ArrayList<String>();
+        List<String> results = new ArrayList<>();
         for (int i = 0; i < splits.length; i++) {
             splits[i] = splits[i].trim();
             if (splits[i].length() > 0) {

zookeeper-server/src/main/java/org/apache/zookeeper/common/ZKConfig.java

@@ -51,7 +51,7 @@ public class ZKConfig {
     public static final String KINIT_COMMAND = "zookeeper.kinit";
     public static final String JGSS_NATIVE = "sun.security.jgss.native";
 
-    private final Map<String, String> properties = new HashMap<String, String>();
+    private final Map<String, String> properties = new HashMap<>();
 
     /**
      * properties, which are common to both client and server, are initialized

zookeeper-server/src/main/java/org/apache/zookeeper/common/ZKHostnameVerifier.java

@@ -320,7 +320,7 @@ final class ZKHostnameVerifier implements HostnameVerifier {
             if (entries == null) {
                 return Collections.emptyList();
             }
-            final List<SubjectName> result = new ArrayList<SubjectName>();
+            final List<SubjectName> result = new ArrayList<>();
             for (List<?> entry : entries) {
                 final Integer type = entry.size() >= 2 ? (Integer) entry.get(0) : null;
                 if (type != null) {

zookeeper-server/src/main/java/org/apache/zookeeper/jmx/MBeanRegistry.java

@@ -47,7 +47,7 @@ public class MBeanRegistry {
 
     private final Object LOCK = new Object();
 
-    private Map<ZKMBeanInfo, String> mapBean2Path = new ConcurrentHashMap<ZKMBeanInfo, String>();
+    private Map<ZKMBeanInfo, String> mapBean2Path = new ConcurrentHashMap<>();
 
     private MBeanServer mBeanServer;
 
@@ -135,7 +135,7 @@ public class MBeanRegistry {
      *         unregistered. Mainly for testing purposes.
      */
     public Set<ZKMBeanInfo> getRegisteredBeans() {
-        return new HashSet<ZKMBeanInfo>(mapBean2Path.keySet());
+        return new HashSet<>(mapBean2Path.keySet());
     }
 
     /**

zookeeper-server/src/main/java/org/apache/zookeeper/server/ContainerManager.java

@@ -48,7 +48,7 @@ public class ContainerManager {
     private final int maxPerMinute;
     private final long maxNeverUsedIntervalMs;
     private final Timer timer;
-    private final AtomicReference<TimerTask> task = new AtomicReference<TimerTask>(null);
+    private final AtomicReference<TimerTask> task = new AtomicReference<>(null);
 
     /**
      * @param zkDb the ZK database
@@ -157,7 +157,7 @@ public class ContainerManager {
 
     // VisibleForTesting
     protected Collection<String> getCandidates() {
-        Set<String> candidates = new HashSet<String>();
+        Set<String> candidates = new HashSet<>();
         for (String containerPath : zkDb.getDataTree().getContainers()) {
             DataNode node = zkDb.getDataTree().getNode(containerPath);
             if ((node != null) && node.getChildren().isEmpty()) {

zookeeper-server/src/main/java/org/apache/zookeeper/server/DataNode.java

@@ -101,7 +101,7 @@ public class DataNode implements Record {
     public synchronized boolean addChild(String child) {
         if (children == null) {
             // let's be conservative on the typical number of children
-            children = new HashSet<String>(8);
+            children = new HashSet<>(8);
         }
         return children.add(child);
     }

zookeeper-server/src/main/java/org/apache/zookeeper/server/DataTree.java

@@ -152,17 +152,17 @@ public class DataTree {
     /**
      * This hashtable lists the paths of the ephemeral nodes of a session.
      */
-    private final Map<Long, HashSet<String>> ephemerals = new ConcurrentHashMap<Long, HashSet<String>>();
+    private final Map<Long, HashSet<String>> ephemerals = new ConcurrentHashMap<>();
 
     /**
      * This set contains the paths of all container nodes
      */
-    private final Set<String> containers = Collections.newSetFromMap(new ConcurrentHashMap<String, Boolean>());
+    private final Set<String> containers = Collections.newSetFromMap(new ConcurrentHashMap<>());
 
     /**
      * This set contains the paths of all ttl nodes
      */
-    private final Set<String> ttls = Collections.newSetFromMap(new ConcurrentHashMap<String, Boolean>());
+    private final Set<String> ttls = Collections.newSetFromMap(new ConcurrentHashMap<>());
 
     private final ReferenceCountedACLCache aclCache = new ReferenceCountedACLCache();
 
@@ -194,7 +194,7 @@ public class DataTree {
     public Set<String> getEphemerals(long sessionId) {
         HashSet<String> retv = ephemerals.get(sessionId);
         if (retv == null) {
-            return new HashSet<String>();
+            return new HashSet<>();
         }
         Set<String> cloned = null;
         synchronized (retv) {
@@ -204,11 +204,11 @@ public class DataTree {
     }
 
     public Set<String> getContainers() {
-        return new HashSet<String>(containers);
+        return new HashSet<>(containers);
     }
 
     public Set<String> getTtls() {
-        return new HashSet<String>(ttls);
+        return new HashSet<>(ttls);
     }
 
     public Collection<Long> getSessions() {
@@ -496,7 +496,7 @@ public class DataTree {
             } else if (ephemeralOwner != 0) {
                 HashSet<String> list = ephemerals.get(ephemeralOwner);
                 if (list == null) {
-                    list = new HashSet<String>();
+                    list = new HashSet<>();
                     ephemerals.put(ephemeralOwner, list);
                 }
                 synchronized (list) {
@@ -730,7 +730,7 @@ public class DataTree {
             if (stat != null) {
                 n.copyStat(stat);
             }
-            children = new ArrayList<String>(n.getChildren());
+            children = new ArrayList<>(n.getChildren());
 
             if (watcher != null) {
                 childWatches.addWatch(path, watcher);
@@ -781,7 +781,7 @@ public class DataTree {
             if (stat != null) {
                 n.copyStat(stat);
             }
-            return new ArrayList<ACL>(aclCache.convertLong(n.acl));
+            return new ArrayList<>(aclCache.convertLong(n.acl));
         }
     }
 
@@ -965,7 +965,7 @@ public class DataTree {
             case OpCode.multi:
                 MultiTxn multiTxn = (MultiTxn) txn;
                 List<Txn> txns = multiTxn.getTxns();
-                rc.multiResult = new ArrayList<ProcessTxnResult>();
+                rc.multiResult = new ArrayList<>();
                 boolean failed = false;
                 for (Txn subtxn : txns) {
                     if (subtxn.getType() == OpCode.error) {
@@ -1389,7 +1389,7 @@ public class DataTree {
                 } else if (eowner != 0) {
                     HashSet<String> list = ephemerals.get(eowner);
                     if (list == null) {
-                        list = new HashSet<String>();
+                        list = new HashSet<>();
                         ephemerals.put(eowner, list);
                     }
                     list.add(path);
@@ -1490,10 +1490,10 @@ public class DataTree {
      * @return map of session ID to sets of ephemeral znodes
      */
     public Map<Long, Set<String>> getEphemerals() {
-        Map<Long, Set<String>> ephemeralsCopy = new HashMap<Long, Set<String>>();
+        Map<Long, Set<String>> ephemeralsCopy = new HashMap<>();
         for (Entry<Long, HashSet<String>> e : ephemerals.entrySet()) {
             synchronized (e.getValue()) {
-                ephemeralsCopy.put(e.getKey(), new HashSet<String>(e.getValue()));
+                ephemeralsCopy.put(e.getKey(), new HashSet<>(e.getValue()));
             }
         }
         return ephemeralsCopy;
@@ -1894,7 +1894,7 @@ public class DataTree {
     public List<ZxidDigest> getDigestLog() {
         synchronized (digestLog) {
             // Return a copy of current digest log
-            return new LinkedList<ZxidDigest>(digestLog);
+            return new LinkedList<>(digestLog);
         }
     }
 

zookeeper-server/src/main/java/org/apache/zookeeper/server/ExpiryQueue.java

@@ -34,13 +34,13 @@ import org.apache.zookeeper.common.Time;
  */
 public class ExpiryQueue<E> {
 
-    private final ConcurrentHashMap<E, Long> elemMap = new ConcurrentHashMap<E, Long>();
+    private final ConcurrentHashMap<E, Long> elemMap = new ConcurrentHashMap<>();
     /**
      * The maximum number of buckets is equal to max timeout/expirationInterval,
      * so the expirationInterval should not be too small compared to the
      * max timeout that this expiry queue needs to maintain.
      */
-    private final ConcurrentHashMap<Long, Set<E>> expiryMap = new ConcurrentHashMap<Long, Set<E>>();
+    private final ConcurrentHashMap<Long, Set<E>> expiryMap = new ConcurrentHashMap<>();
 
     private final AtomicLong nextExpirationTime = new AtomicLong();
     private final int expirationInterval;
@@ -95,7 +95,7 @@ public class ExpiryQueue<E> {
         Set<E> set = expiryMap.get(newExpiryTime);
         if (set == null) {
             // Construct a ConcurrentHashSet using a ConcurrentHashMap
-            set = Collections.newSetFromMap(new ConcurrentHashMap<E, Boolean>());
+            set = Collections.newSetFromMap(new ConcurrentHashMap<>());
             // Put the new set in the map, but only if another thread
             // hasn't beaten us to it
             Set<E> existingSet = expiryMap.putIfAbsent(newExpiryTime, set);
@@ -158,7 +158,7 @@ public class ExpiryQueue<E> {
         pwriter.print(")/(");
         pwriter.print(elemMap.size());
         pwriter.println("):");
-        ArrayList<Long> keys = new ArrayList<Long>(expiryMap.keySet());
+        ArrayList<Long> keys = new ArrayList<>(expiryMap.keySet());
         Collections.sort(keys);
         for (long time : keys) {
             Set<E> set = expiryMap.get(time);

zookeeper-server/src/main/java/org/apache/zookeeper/server/FinalRequestProcessor.java

@@ -442,7 +442,7 @@ public class FinalRequestProcessor implements RequestProcessor {
                         null);
                     rsp = new GetACLResponse(acl, stat);
                 } catch (KeeperException.NoAuthException e) {
-                    List<ACL> acl1 = new ArrayList<ACL>(acl.size());
+                    List<ACL> acl1 = new ArrayList<>(acl.size());
                     for (ACL a : acl) {
                         if ("digest".equals(a.getId().getScheme())) {
                             Id id = a.getId();

zookeeper-server/src/main/java/org/apache/zookeeper/server/NIOServerCnxn.java

@@ -74,7 +74,7 @@ public class NIOServerCnxn extends ServerCnxn {
 
     protected ByteBuffer incomingBuffer = lenBuffer;
 
-    private final Queue<ByteBuffer> outgoingBuffers = new LinkedBlockingQueue<ByteBuffer>();
+    private final Queue<ByteBuffer> outgoingBuffers = new LinkedBlockingQueue<>();
 
     private int sessionTimeout;
 

zookeeper-server/src/main/java/org/apache/zookeeper/server/NIOServerCnxnFactory.java

@@ -324,8 +324,8 @@ public class NIOServerCnxnFactory extends ServerCnxnFactory {
         public SelectorThread(int id) throws IOException {
             super("NIOServerCxnFactory.SelectorThread-" + id);
             this.id = id;
-            acceptedQueue = new LinkedBlockingQueue<SocketChannel>();
-            updateQueue = new LinkedBlockingQueue<SelectionKey>();
+            acceptedQueue = new LinkedBlockingQueue<>();
+            updateQueue = new LinkedBlockingQueue<>();
         }
 
         /**
@@ -403,7 +403,7 @@ public class NIOServerCnxnFactory extends ServerCnxnFactory {
                 selector.select();
 
                 Set<SelectionKey> selected = selector.selectedKeys();
-                ArrayList<SelectionKey> selectedList = new ArrayList<SelectionKey>(selected);
+                ArrayList<SelectionKey> selectedList = new ArrayList<>(selected);
                 Collections.shuffle(selectedList);
                 Iterator<SelectionKey> selectedKeys = selectedList.iterator();
                 while (!stopped && selectedKeys.hasNext()) {
@@ -587,7 +587,7 @@ public class NIOServerCnxnFactory extends ServerCnxnFactory {
     }
 
     // ipMap is used to limit connections per IP
-    private final ConcurrentHashMap<InetAddress, Set<NIOServerCnxn>> ipMap = new ConcurrentHashMap<InetAddress, Set<NIOServerCnxn>>();
+    private final ConcurrentHashMap<InetAddress, Set<NIOServerCnxn>> ipMap = new ConcurrentHashMap<>();
 
     protected int maxClientCnxns = 60;
     int listenBacklog = -1;
@@ -613,7 +613,7 @@ public class NIOServerCnxnFactory extends ServerCnxnFactory {
     private volatile boolean stopped = true;
     private ConnectionExpirerThread expirerThread;
     private AcceptThread acceptThread;
-    private final Set<SelectorThread> selectorThreads = new HashSet<SelectorThread>();
+    private final Set<SelectorThread> selectorThreads = new HashSet<>();
 
     @Override
     public void configure(InetSocketAddress addr, int maxcc, int backlog, boolean secure) throws IOException {
@@ -629,7 +629,7 @@ public class NIOServerCnxnFactory extends ServerCnxnFactory {
         // cnxnExpiryQueue. These don't need to be the same, but the expiring
         // interval passed into the ExpiryQueue() constructor below should be
         // less than or equal to the timeout.
-        cnxnExpiryQueue = new ExpiryQueue<NIOServerCnxn>(sessionlessCnxnTimeout);
+        cnxnExpiryQueue = new ExpiryQueue<>(sessionlessCnxnTimeout);
         expirerThread = new ConnectionExpirerThread();
 
         int numCores = Runtime.getRuntime().availableProcessors();
@@ -809,7 +809,7 @@ public class NIOServerCnxnFactory extends ServerCnxnFactory {
             // of 1 entry --  we need to set the initial cap
             // to 2 to avoid rehash when the first entry is added
             // Construct a ConcurrentHashSet using a ConcurrentHashMap
-            set = Collections.newSetFromMap(new ConcurrentHashMap<NIOServerCnxn, Boolean>(2));
+            set = Collections.newSetFromMap(new ConcurrentHashMap<>(2));
             // Put the new set in the map, but only if another thread
             // hasn't beaten us to it
             Set<NIOServerCnxn> existingSet = ipMap.putIfAbsent(addr, set);
@@ -946,7 +946,7 @@ public class NIOServerCnxnFactory extends ServerCnxnFactory {
 
     @Override
     public Iterable<Map<String, Object>> getAllConnectionInfo(boolean brief) {
-        HashSet<Map<String, Object>> info = new HashSet<Map<String, Object>>();
+        HashSet<Map<String, Object>> info = new HashSet<>();
         // No need to synchronize since cnxns is backed by a ConcurrentHashMap
         for (ServerCnxn c : cnxns) {
             info.add(c.getConnectionInfo(brief));

zookeeper-server/src/main/java/org/apache/zookeeper/server/NettyServerCnxnFactory.java

@@ -809,7 +809,7 @@ public class NettyServerCnxnFactory extends ServerCnxnFactory {
 
     @Override
     public Iterable<Map<String, Object>> getAllConnectionInfo(boolean brief) {
-        Set<Map<String, Object>> info = new HashSet<Map<String, Object>>();
+        Set<Map<String, Object>> info = new HashSet<>();
         // No need to synchronize since cnxns is backed by a ConcurrentHashMap
         for (ServerCnxn c : cnxns) {
             info.add(c.getConnectionInfo(brief));

zookeeper-server/src/main/java/org/apache/zookeeper/server/PrepRequestProcessor.java

@@ -214,7 +214,7 @@ public class PrepRequestProcessor extends ZooKeeperCriticalThread implements Req
      *         rolled back in any failure.
      */
     private Map<String, ChangeRecord> getPendingChanges(MultiOperationRecord multiRequest) {
-        Map<String, ChangeRecord> pendingChangeRecords = new HashMap<String, ChangeRecord>();
+        Map<String, ChangeRecord> pendingChangeRecords = new HashMap<>();
 
         for (Op op : multiRequest) {
             String path = op.getPath();
@@ -467,7 +467,7 @@ public class PrepRequestProcessor extends ZooKeeperCriticalThread implements Req
                     LOG.warn(msg);
                     throw new KeeperException.BadArgumentsException(msg);
                 }
-                Map<Long, QuorumServer> nextServers = new HashMap<Long, QuorumServer>(lastSeenQV.getAllMembers());
+                Map<Long, QuorumServer> nextServers = new HashMap<>(lastSeenQV.getAllMembers());
                 try {
                     if (leavingServers != null) {
                         for (String leaving : leavingServers) {

zookeeper-server/src/main/java/org/apache/zookeeper/server/PurgeTxnLog.java

@@ -109,7 +109,7 @@ public class PurgeTxnLog {
          * recoverability of all snapshots being retained.  We determine that log file here by
          * calling txnLog.getSnapshotLogs().
          */
-        final Set<File> retainedTxnLogs = new HashSet<File>();
+        final Set<File> retainedTxnLogs = new HashSet<>();
         retainedTxnLogs.addAll(Arrays.asList(txnLog.getSnapshotLogs(leastZxidToBeRetain)));
 
         /**

zookeeper-server/src/main/java/org/apache/zookeeper/server/ReferenceCountedACLCache.java

@@ -38,11 +38,11 @@ public class ReferenceCountedACLCache {
 
     private static final Logger LOG = LoggerFactory.getLogger(ReferenceCountedACLCache.class);
 
-    final Map<Long, List<ACL>> longKeyMap = new HashMap<Long, List<ACL>>();
+    final Map<Long, List<ACL>> longKeyMap = new HashMap<>();
 
-    final Map<List<ACL>, Long> aclKeyMap = new HashMap<List<ACL>, Long>();
+    final Map<List<ACL>, Long> aclKeyMap = new HashMap<>();
 
-    final Map<Long, AtomicLongWithEquals> referenceCounter = new HashMap<Long, AtomicLongWithEquals>();
+    final Map<Long, AtomicLongWithEquals> referenceCounter = new HashMap<>();
     private static final long OPEN_UNSAFE_ACL_ID = -1L;
 
     /**
@@ -107,7 +107,7 @@ public class ReferenceCountedACLCache {
         // keep read operations out of synchronization block
         while (i > 0) {
             Long val = ia.readLong("long");
-            List<ACL> aclList = new ArrayList<ACL>();
+            List<ACL> aclList = new ArrayList<>();
             Index j = ia.startVector("acls");
             if (j == null) {
                 throw new RuntimeException("Incorrent format of InputArchive when deserialize DataTree - missing acls");

zookeeper-server/src/main/java/org/apache/zookeeper/server/RequestThrottler.java

@@ -61,7 +61,7 @@ public class RequestThrottler extends ZooKeeperCriticalThread {
 
     private static final Logger LOG = LoggerFactory.getLogger(RequestThrottler.class);
 
-    private final LinkedBlockingQueue<Request> submittedRequests = new LinkedBlockingQueue<Request>();
+    private final LinkedBlockingQueue<Request> submittedRequests = new LinkedBlockingQueue<>();
 
     private final ZooKeeperServer zks;
     private volatile boolean stopping;

zookeeper-server/src/main/java/org/apache/zookeeper/server/ServerCnxn.java

@@ -547,7 +547,7 @@ public abstract class ServerCnxn implements Stats, Watcher {
     }
 
     public synchronized Map<String, Object> getConnectionInfo(boolean brief) {
-        Map<String, Object> info = new LinkedHashMap<String, Object>();
+        Map<String, Object> info = new LinkedHashMap<>();
         info.put("remote_socket_address", getRemoteSocketAddress());
         info.put("interest_ops", getInterestOps());
         info.put("outstanding_requests", getOutstandingRequests());

zookeeper-server/src/main/java/org/apache/zookeeper/server/ServerCnxnFactory.java

@@ -57,7 +57,7 @@ public abstract class ServerCnxnFactory {
     protected int maxCnxns;
 
     // sessionMap is used by closeSession()
-    final ConcurrentHashMap<Long, ServerCnxn> sessionMap = new ConcurrentHashMap<Long, ServerCnxn>();
+    final ConcurrentHashMap<Long, ServerCnxn> sessionMap = new ConcurrentHashMap<>();
 
     private static String loginUser = Login.SYSTEM_USER;
 
@@ -198,11 +198,11 @@ public abstract class ServerCnxnFactory {
 
     public abstract Iterable<Map<String, Object>> getAllConnectionInfo(boolean brief);
 
-    private final ConcurrentHashMap<ServerCnxn, ConnectionBean> connectionBeans = new ConcurrentHashMap<ServerCnxn, ConnectionBean>();
+    private final ConcurrentHashMap<ServerCnxn, ConnectionBean> connectionBeans = new ConcurrentHashMap<>();
 
     // Connection set is relied on heavily by four letter commands
     // Construct a ConcurrentHashSet using a ConcurrentHashMap
-    protected final Set<ServerCnxn> cnxns = Collections.newSetFromMap(new ConcurrentHashMap<ServerCnxn, Boolean>());
+    protected final Set<ServerCnxn> cnxns = Collections.newSetFromMap(new ConcurrentHashMap<>());
     public void unregisterConnection(ServerCnxn serverCnxn) {
         ConnectionBean jmxConnectionBean = connectionBeans.remove(serverCnxn);
         if (jmxConnectionBean != null) {

zookeeper-server/src/main/java/org/apache/zookeeper/server/SessionTrackerImpl.java

@@ -46,7 +46,7 @@ public class SessionTrackerImpl extends ZooKeeperCriticalThread implements Sessi
 
     private static final Logger LOG = LoggerFactory.getLogger(SessionTrackerImpl.class);
 
-    protected final ConcurrentHashMap<Long, SessionImpl> sessionsById = new ConcurrentHashMap<Long, SessionImpl>();
+    protected final ConcurrentHashMap<Long, SessionImpl> sessionsById = new ConcurrentHashMap<>();
 
     private final ExpiryQueue<SessionImpl> sessionExpiryQueue;
 
@@ -110,7 +110,7 @@ public class SessionTrackerImpl extends ZooKeeperCriticalThread implements Sessi
     public SessionTrackerImpl(SessionExpirer expirer, ConcurrentMap<Long, Integer> sessionsWithTimeout, int tickTime, long serverId, ZooKeeperServerListener listener) {
         super("SessionTracker", listener);
         this.expirer = expirer;
-        this.sessionExpiryQueue = new ExpiryQueue<SessionImpl>(tickTime);
+        this.sessionExpiryQueue = new ExpiryQueue<>(tickTime);
         this.sessionsWithTimeout = sessionsWithTimeout;
         this.nextSessionId.set(initializeNextSessionId(serverId));
         for (Entry<Long, Integer> e : sessionsWithTimeout.entrySet()) {
@@ -133,9 +133,9 @@ public class SessionTrackerImpl extends ZooKeeperCriticalThread implements Sessi
     public synchronized Map<Long, Set<Long>> getSessionExpiryMap() {
         // Convert time -> sessions map to time -> session IDs map
         Map<Long, Set<SessionImpl>> expiryMap = sessionExpiryQueue.getExpiryMap();
-        Map<Long, Set<Long>> sessionExpiryMap = new TreeMap<Long, Set<Long>>();
+        Map<Long, Set<Long>> sessionExpiryMap = new TreeMap<>();
         for (Entry<Long, Set<SessionImpl>> e : expiryMap.entrySet()) {
-            Set<Long> ids = new HashSet<Long>();
+            Set<Long> ids = new HashSet<>();
             sessionExpiryMap.put(e.getKey(), ids);
             for (SessionImpl s : e.getValue()) {
                 ids.add(s.sessionId);

zookeeper-server/src/main/java/org/apache/zookeeper/server/SnapshotComparer.java

@@ -169,7 +169,7 @@ public class SnapshotComparer {
       public TreeNode(String label, long size) {
         this.label = label;
         this.size = size;
-        this.children = new ArrayList<TreeNode>();
+        this.children = new ArrayList<>();
       }
 
       void populateChildren(String path, DataTree dataTree, TreeInfo treeInfo) throws Exception {
@@ -208,8 +208,8 @@ public class SnapshotComparer {
 
     final TreeNode root;
     long count;
-    List<ArrayList<TreeNode>> nodesAtDepths = new ArrayList<ArrayList<TreeNode>>();
-    Map<String, TreeNode> nodesByName = new HashMap<String, TreeNode>();
+    List<ArrayList<TreeNode>> nodesAtDepths = new ArrayList<>();
+    Map<String, TreeNode> nodesByName = new HashMap<>();
 
     TreeInfo(File snapshot) throws Exception {
       DataTree dataTree = getSnapshot(snapshot);
@@ -229,7 +229,7 @@ public class SnapshotComparer {
 
     void registerNode(TreeNode node, int depth) {
       while (depth > nodesAtDepths.size()) {
-        nodesAtDepths.add(new ArrayList<TreeNode>());
+        nodesAtDepths.add(new ArrayList<>());
       }
       nodesAtDepths.get(depth - 1).add(node);
       nodesByName.put(node.label, node);
@@ -261,7 +261,7 @@ public class SnapshotComparer {
   private static DataTree getSnapshot(File file) throws Exception {
     FileSnap fileSnap = new FileSnap(null);
     DataTree dataTree = new DataTree();
-    Map<Long, Integer> sessions = new HashMap<Long, Integer>();
+    Map<Long, Integer> sessions = new HashMap<>();
     CheckedInputStream snapIS = SnapStream.getInputStream(file);
 
     long beginning = System.nanoTime();

zookeeper-server/src/main/java/org/apache/zookeeper/server/SnapshotFormatter.java

@@ -99,7 +99,7 @@ public class SnapshotFormatter {
             FileSnap fileSnap = new FileSnap(null);
 
             DataTree dataTree = new DataTree();
-            Map<Long, Integer> sessions = new HashMap<Long, Integer>();
+            Map<Long, Integer> sessions = new HashMap<>();
 
             fileSnap.deserialize(dataTree, sessions, ia);
             long fileNameZxid = Util.getZxidFromName(snapshotFile.getName(), SNAPSHOT_FILE_PREFIX);

zookeeper-server/src/main/java/org/apache/zookeeper/server/SnapshotRecursiveSummary.java

@@ -70,7 +70,7 @@ import org.apache.zookeeper.server.persistence.SnapStream;
       FileSnap fileSnap = new FileSnap(null);
 
       DataTree dataTree = new DataTree();
-      Map<Long, Integer> sessions = new HashMap<Long, Integer>();
+      Map<Long, Integer> sessions = new HashMap<>();
 
       fileSnap.deserialize(dataTree, sessions, ia);
 

zookeeper-server/src/main/java/org/apache/zookeeper/server/SyncRequestProcessor.java

@@ -69,7 +69,7 @@ public class SyncRequestProcessor extends ZooKeeperCriticalThread implements Req
     private int randRoll;
     private long randSize;
 
-    private final BlockingQueue<Request> queuedRequests = new LinkedBlockingQueue<Request>();
+    private final BlockingQueue<Request> queuedRequests = new LinkedBlockingQueue<>();
 
     private final Semaphore snapThreadMutex = new Semaphore(1);
 

zookeeper-server/src/main/java/org/apache/zookeeper/server/WorkerService.java

@@ -47,7 +47,7 @@ public class WorkerService {
 
     private static final Logger LOG = LoggerFactory.getLogger(WorkerService.class);
 
-    private final ArrayList<ExecutorService> workers = new ArrayList<ExecutorService>();
+    private final ArrayList<ExecutorService> workers = new ArrayList<>();
 
     private final String threadNamePrefix;
     private int numWorkerThreads;

zookeeper-server/src/main/java/org/apache/zookeeper/server/ZKDatabase.java

@@ -110,7 +110,7 @@ public class ZKDatabase {
      */
     public ZKDatabase(FileTxnSnapLog snapLog) {
         dataTree = createDataTree();
-        sessionsWithTimeouts = new ConcurrentHashMap<Long, Integer>();
+        sessionsWithTimeouts = new ConcurrentHashMap<>();
         this.snapLog = snapLog;
 
         try {

zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServer.java

@@ -241,7 +241,7 @@ public class ZooKeeperServer implements SessionExpirer, ServerStats.Provider {
     private final AtomicInteger requestsInProcess = new AtomicInteger(0);
     final Deque<ChangeRecord> outstandingChanges = new ArrayDeque<>();
     // this data structure must be accessed under the outstandingChanges lock
-    final Map<String, ChangeRecord> outstandingChangesForPath = new HashMap<String, ChangeRecord>();
+    final Map<String, ChangeRecord> outstandingChangesForPath = new HashMap<>();
 
     protected ServerCnxnFactory serverCnxnFactory;
     protected ServerCnxnFactory secureServerCnxnFactory;

zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServerConf.java

@@ -187,7 +187,7 @@ public class ZooKeeperServerConf {
      * @return map representation of configuration
      */
     public Map<String, Object> toMap() {
-        Map<String, Object> conf = new LinkedHashMap<String, Object>();
+        Map<String, Object> conf = new LinkedHashMap<>();
         conf.put(KEY_CLIENT_PORT, clientPort);
         conf.put(KEY_DATA_DIR, dataDir);
         conf.put(KEY_DATA_LOG_DIR, dataLogDir);

zookeeper-server/src/main/java/org/apache/zookeeper/server/admin/CommandBase.java

@@ -41,7 +41,7 @@ public abstract class CommandBase implements Command {
 
     protected CommandBase(List<String> names, boolean serverRequired, String doc) {
         this.primaryName = names.get(0);
-        this.names = new HashSet<String>(names);
+        this.names = new HashSet<>(names);
         this.doc = doc;
         this.serverRequired = serverRequired;
     }

zookeeper-server/src/main/java/org/apache/zookeeper/server/admin/CommandResponse.java

@@ -75,7 +75,7 @@ public class CommandResponse {
     public CommandResponse(final String command, final String error, final int statusCode, final InputStream inputStream) {
         this.command = command;
         this.error = error;
-        data = new LinkedHashMap<String, Object>();
+        data = new LinkedHashMap<>();
         headers = new HashMap<>();
         this.statusCode = statusCode;
         this.inputStream = inputStream;
@@ -177,7 +177,7 @@ public class CommandResponse {
      * @return map representation of response
      */
     public Map<String, Object> toMap() {
-        Map<String, Object> m = new LinkedHashMap<String, Object>(data);
+        Map<String, Object> m = new LinkedHashMap<>(data);
         m.put(KEY_COMMAND, command);
         m.put(KEY_ERROR, error);
         m.putAll(data);

zookeeper-server/src/main/java/org/apache/zookeeper/server/admin/Commands.java

@@ -78,8 +78,8 @@ public class Commands {
     private static final long rateLimiterInterval = Integer.parseInt(System.getProperty(ADMIN_RATE_LIMITER_INTERVAL, "300000"));
 
     /** Maps command names to Command instances */
-    private static Map<String, Command> commands = new HashMap<String, Command>();
-    private static Set<String> primaryNames = new HashSet<String>();
+    private static Map<String, Command> commands = new HashMap<>();
+    private static Set<String> primaryNames = new HashSet<>();
 
     /**
      * Registers the given command. Registered commands can be run by passing

zookeeper-server/src/main/java/org/apache/zookeeper/server/admin/JettyAdminServer.java

@@ -255,7 +255,7 @@ public class JettyAdminServer implements AdminServer {
 
             // Extract keyword arguments to command from request parameters
             @SuppressWarnings("unchecked") Map<String, String[]> parameterMap = request.getParameterMap();
-            Map<String, String> kwargs = new HashMap<String, String>();
+            Map<String, String> kwargs = new HashMap<>();
             for (Map.Entry<String, String[]> entry : parameterMap.entrySet()) {
                 kwargs.put(entry.getKey(), entry.getValue()[0]);
             }

zookeeper-server/src/main/java/org/apache/zookeeper/server/auth/EnsembleAuthenticationProvider.java

@@ -52,7 +52,7 @@ public class EnsembleAuthenticationProvider implements AuthenticationProvider {
     }
 
     public void setEnsembleNames(String namesCSV) {
-        ensembleNames = new HashSet<String>();
+        ensembleNames = new HashSet<>();
         for (String name : namesCSV.split(",")) {
             ensembleNames.add(name.trim());
         }

zookeeper-server/src/main/java/org/apache/zookeeper/server/auth/KerberosName.java

@@ -322,7 +322,7 @@ public class KerberosName {
     }
 
     static List<Rule> parseRules(String rules) {
-        List<Rule> result = new ArrayList<Rule>();
+        List<Rule> result = new ArrayList<>();
         String remaining = rules.trim();
         while (remaining.length() > 0) {
             Matcher matcher = ruleParser.matcher(remaining);

zookeeper-server/src/main/java/org/apache/zookeeper/server/auth/SaslServerCallbackHandler.java

@@ -43,7 +43,7 @@ public class SaslServerCallbackHandler implements CallbackHandler {
     private static final String SYSPROP_REMOVE_REALM = "zookeeper.kerberos.removeRealmFromPrincipal";
 
     private String userName;
-    private final Map<String, String> credentials = new HashMap<String, String>();
+    private final Map<String, String> credentials = new HashMap<>();
 
     public SaslServerCallbackHandler(Configuration configuration) throws IOException {
         String serverSection = System.getProperty(

zookeeper-server/src/main/java/org/apache/zookeeper/server/command/FourLetterCommands.java

@@ -151,9 +151,9 @@ public class FourLetterCommands {
 
     private static final Logger LOG = LoggerFactory.getLogger(FourLetterCommands.class);
 
-    private static final Map<Integer, String> cmd2String = new HashMap<Integer, String>();
+    private static final Map<Integer, String> cmd2String = new HashMap<>();
 
-    private static final Set<String> whiteListedCommands = new HashSet<String>();
+    private static final Set<String> whiteListedCommands = new HashSet<>();
 
     private static boolean whiteListInitialized = false;
 

zookeeper-server/src/main/java/org/apache/zookeeper/server/metric/AvgMinMaxCounter.java

@@ -109,7 +109,7 @@ public class AvgMinMaxCounter extends Metric implements Summary {
     }
 
     public Map<String, Object> values() {
-        Map<String, Object> m = new LinkedHashMap<String, Object>();
+        Map<String, Object> m = new LinkedHashMap<>();
         m.put("avg_" + name, this.getAvg());
         m.put("min_" + name, this.getMin());
         m.put("max_" + name, this.getMax());

zookeeper-server/src/main/java/org/apache/zookeeper/server/metric/AvgMinMaxPercentileCounter.java

@@ -84,7 +84,7 @@ public class AvgMinMaxPercentileCounter extends Metric implements Summary {
         @Override
         public Snapshot getSnapshot() {
             final int s = size();
-            final List<Long> copy = new ArrayList<Long>(s);
+            final List<Long> copy = new ArrayList<>(s);
             for (int i = 0; i < s; i++) {
                 copy.add(values.get(i));
             }

zookeeper-server/src/main/java/org/apache/zookeeper/server/metric/SimpleCounter.java

@@ -48,7 +48,7 @@ public class SimpleCounter extends Metric implements Counter {
 
     @Override
     public Map<String, Object> values() {
-        Map<String, Object> m = new LinkedHashMap<String, Object>();
+        Map<String, Object> m = new LinkedHashMap<>();
         m.put(name, this.get());
         return m;
     }

zookeeper-server/src/main/java/org/apache/zookeeper/server/persistence/FileSnap.java

@@ -166,7 +166,7 @@ public class FileSnap implements SnapShot {
     protected List<File> findNValidSnapshots(int n) {
         List<File> files = Util.sortDataDir(snapDir.listFiles(), SNAPSHOT_FILE_PREFIX, false);
         int count = 0;
-        List<File> list = new ArrayList<File>();
+        List<File> list = new ArrayList<>();
         for (File f : files) {
             // we should catch the exceptions
             // from the valid snapshot and continue
@@ -196,7 +196,7 @@ public class FileSnap implements SnapShot {
     public List<File> findNRecentSnapshots(int n) throws IOException {
         List<File> files = Util.sortDataDir(snapDir.listFiles(), SNAPSHOT_FILE_PREFIX, false);
         int count = 0;
-        List<File> list = new ArrayList<File>();
+        List<File> list = new ArrayList<>();
         for (File f : files) {
             if (count == n) {
                 break;

zookeeper-server/src/main/java/org/apache/zookeeper/server/persistence/FileTxnLog.java

@@ -332,7 +332,7 @@ public class FileTxnLog implements TxnLog, Closeable {
                 logZxid = fzxid;
             }
         }
-        List<File> v = new ArrayList<File>(5);
+        List<File> v = new ArrayList<>(5);
         for (File f : files) {
             long fzxid = Util.getZxidFromName(f.getName(), LOG_FILE_PREFIX);
             if (fzxid < logZxid) {

zookeeper-server/src/main/java/org/apache/zookeeper/server/persistence/Util.java

@@ -248,7 +248,7 @@ public class Util {
      */
     public static List<File> sortDataDir(File[] files, String prefix, boolean ascending) {
         if (files == null) {
-            return new ArrayList<File>(0);
+            return new ArrayList<>(0);
         }
         List<File> filelist = Arrays.asList(files);
         Collections.sort(filelist, new DataDirFileComparator(prefix, ascending));

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/CommitProcessor.java

@@ -90,7 +90,7 @@ public class CommitProcessor extends ZooKeeperCriticalThread implements RequestP
     /**
      * Incoming requests.
      */
-    protected LinkedBlockingQueue<Request> queuedRequests = new LinkedBlockingQueue<Request>();
+    protected LinkedBlockingQueue<Request> queuedRequests = new LinkedBlockingQueue<>();
 
     /**
      * Incoming requests that are waiting on a commit,
@@ -111,7 +111,7 @@ public class CommitProcessor extends ZooKeeperCriticalThread implements RequestP
     /**
      * Requests that have been committed.
      */
-    protected final LinkedBlockingQueue<Request> committedRequests = new LinkedBlockingQueue<Request>();
+    protected final LinkedBlockingQueue<Request> committedRequests = new LinkedBlockingQueue<>();
 
     /**
      * Requests that we are holding until commit comes in. Keys represent

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/FastLeaderElection.java

@@ -646,8 +646,8 @@ public class FastLeaderElection implements Election {
         proposedLeader = -1;
         proposedZxid = -1;
 
-        sendqueue = new LinkedBlockingQueue<ToSend>();
-        recvqueue = new LinkedBlockingQueue<Notification>();
+        sendqueue = new LinkedBlockingQueue<>();
+        recvqueue = new LinkedBlockingQueue<>();
         this.messenger = new Messenger(manager);
     }
 
@@ -925,7 +925,7 @@ public class FastLeaderElection implements Election {
              * if v.electionEpoch == logicalclock. The current participant uses recvset to deduce on whether a majority
              * of participants has voted for it.
              */
-            Map<Long, Vote> recvset = new HashMap<Long, Vote>();
+            Map<Long, Vote> recvset = new HashMap<>();
 
             /*
              * The votes from previous leader elections, as well as the votes from the current leader election are
@@ -934,7 +934,7 @@ public class FastLeaderElection implements Election {
              * outofelection to learn which participant is the leader if it arrives late (i.e., higher logicalclock than
              * the electionEpoch of the received notifications) in a leader election.
              */
-            Map<Long, Vote> outofelection = new HashMap<Long, Vote>();
+            Map<Long, Vote> outofelection = new HashMap<>();
 
             int notTimeout = minNotificationInterval;
 

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/FollowerRequestProcessor.java

@@ -47,7 +47,7 @@ public class FollowerRequestProcessor extends ZooKeeperCriticalThread implements
 
     RequestProcessor nextProcessor;
 
-    LinkedBlockingQueue<Request> queuedRequests = new LinkedBlockingQueue<Request>();
+    LinkedBlockingQueue<Request> queuedRequests = new LinkedBlockingQueue<>();
 
     boolean finished = false;
 

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/FollowerZooKeeperServer.java

@@ -59,7 +59,7 @@ public class FollowerZooKeeperServer extends LearnerZooKeeperServer {
      */
     FollowerZooKeeperServer(FileTxnSnapLog logFactory, QuorumPeer self, ZKDatabase zkDb) throws IOException {
         super(logFactory, self.tickTime, self.minSessionTimeout, self.maxSessionTimeout, self.clientPortListenBacklog, zkDb, self);
-        this.pendingSyncs = new ConcurrentLinkedQueue<Request>();
+        this.pendingSyncs = new ConcurrentLinkedQueue<>();
     }
 
     public Follower getFollower() {
@@ -77,7 +77,7 @@ public class FollowerZooKeeperServer extends LearnerZooKeeperServer {
         syncProcessor.start();
     }
 
-    LinkedBlockingQueue<Request> pendingTxns = new LinkedBlockingQueue<Request>();
+    LinkedBlockingQueue<Request> pendingTxns = new LinkedBlockingQueue<>();
 
     public void logRequest(TxnHeader hdr, Record txn, TxnDigest digest) {
         Request request = new Request(hdr.getClientId(), hdr.getCxid(), hdr.getType(), hdr, txn, hdr.getZxid());

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/Leader.java

@@ -127,7 +127,7 @@ public class Leader extends LearnerMaster {
     volatile LearnerCnxAcceptor cnxAcceptor = null;
 
     // list of all the learners, including followers and observers
-    private final HashSet<LearnerHandler> learners = new HashSet<LearnerHandler>();
+    private final HashSet<LearnerHandler> learners = new HashSet<>();
 
     private final BufferStats proposalStats;
 
@@ -143,24 +143,24 @@ public class Leader extends LearnerMaster {
      */
     public List<LearnerHandler> getLearners() {
         synchronized (learners) {
-            return new ArrayList<LearnerHandler>(learners);
+            return new ArrayList<>(learners);
         }
     }
 
     // list of followers that are ready to follow (i.e synced with the leader)
-    private final HashSet<LearnerHandler> forwardingFollowers = new HashSet<LearnerHandler>();
+    private final HashSet<LearnerHandler> forwardingFollowers = new HashSet<>();
 
     /**
      * Returns a copy of the current forwarding follower snapshot
      */
     public List<LearnerHandler> getForwardingFollowers() {
         synchronized (forwardingFollowers) {
-            return new ArrayList<LearnerHandler>(forwardingFollowers);
+            return new ArrayList<>(forwardingFollowers);
         }
     }
 
     public List<LearnerHandler> getNonVotingFollowers() {
-        List<LearnerHandler> nonVotingFollowers = new ArrayList<LearnerHandler>();
+        List<LearnerHandler> nonVotingFollowers = new ArrayList<>();
         synchronized (forwardingFollowers) {
             for (LearnerHandler lh : forwardingFollowers) {
                 if (!isParticipant(lh.getSid())) {
@@ -181,14 +181,14 @@ public class Leader extends LearnerMaster {
         }
     }
 
-    private final HashSet<LearnerHandler> observingLearners = new HashSet<LearnerHandler>();
+    private final HashSet<LearnerHandler> observingLearners = new HashSet<>();
 
     /**
      * Returns a copy of the current observer snapshot
      */
     public List<LearnerHandler> getObservingLearners() {
         synchronized (observingLearners) {
-            return new ArrayList<LearnerHandler>(observingLearners);
+            return new ArrayList<>(observingLearners);
         }
     }
 
@@ -217,7 +217,7 @@ public class Leader extends LearnerMaster {
     }
 
     // Pending sync requests. Must access under 'this' lock.
-    private final Map<Long, List<LearnerSyncRequest>> pendingSyncs = new HashMap<Long, List<LearnerSyncRequest>>();
+    private final Map<Long, List<LearnerSyncRequest>> pendingSyncs = new HashMap<>();
 
     public synchronized int getNumPendingSyncs() {
         return pendingSyncs.size();
@@ -270,7 +270,7 @@ public class Leader extends LearnerMaster {
      * @param qv is a QuorumVerifier
      */
     public boolean isQuorumSynced(QuorumVerifier qv) {
-        HashSet<Long> ids = new HashSet<Long>();
+        HashSet<Long> ids = new HashSet<>();
         if (qv.getVotingMembers().containsKey(self.getMyId())) {
             ids.add(self.getMyId());
         }
@@ -430,9 +430,9 @@ public class Leader extends LearnerMaster {
      */
     static final int INFORMANDACTIVATE = 19;
 
-    final ConcurrentMap<Long, Proposal> outstandingProposals = new ConcurrentHashMap<Long, Proposal>();
+    final ConcurrentMap<Long, Proposal> outstandingProposals = new ConcurrentHashMap<>();
 
-    private final ConcurrentLinkedQueue<Proposal> toBeApplied = new ConcurrentLinkedQueue<Proposal>();
+    private final ConcurrentLinkedQueue<Proposal> toBeApplied = new ConcurrentLinkedQueue<>();
 
     // VisibleForTesting
     protected final Proposal newLeaderProposal = new Proposal();
@@ -669,7 +669,7 @@ public class Leader extends LearnerMaster {
                 shutdown("Waiting for a quorum of followers, only synced with sids: [ "
                          + newLeaderProposal.ackSetsToString()
                          + " ]");
-                HashSet<Long> followerSet = new HashSet<Long>();
+                HashSet<Long> followerSet = new HashSet<>();
 
                 for (LearnerHandler f : getLearners()) {
                     if (self.getQuorumVerifier().getVotingMembers().containsKey(f.getSid())) {
@@ -877,7 +877,7 @@ public class Leader extends LearnerMaster {
         // start with an initial set of candidates that are voters from new config that
         // acknowledged the reconfig op (there must be a quorum). Choose one of them as
         // current leader candidate
-        HashSet<Long> candidates = new HashSet<Long>(newQVAcksetPair.getAckset());
+        HashSet<Long> candidates = new HashSet<>(newQVAcksetPair.getAckset());
         candidates.remove(self.getMyId()); // if we're here, I shouldn't be the leader
         long curCandidate = candidates.iterator().next();
 
@@ -1326,7 +1326,7 @@ public class Leader extends LearnerMaster {
             }
             // Only participant need to get outstanding proposals
             if (handler.getLearnerType() == LearnerType.PARTICIPANT) {
-                List<Long> zxids = new ArrayList<Long>(outstandingProposals.keySet());
+                List<Long> zxids = new ArrayList<>(outstandingProposals.keySet());
                 Collections.sort(zxids);
                 for (Long zxid : zxids) {
                     if (zxid <= lastSeenZxid) {
@@ -1355,7 +1355,7 @@ public class Leader extends LearnerMaster {
     }
 
     // VisibleForTesting
-    protected final Set<Long> connectingFollowers = new HashSet<Long>();
+    protected final Set<Long> connectingFollowers = new HashSet<>();
 
     private volatile boolean quitWaitForEpoch = false;
     private volatile long timeStartWaitForEpoch = -1;
@@ -1453,7 +1453,7 @@ public class Leader extends LearnerMaster {
     }
 
     // VisibleForTesting
-    protected final Set<Long> electingFollowers = new HashSet<Long>();
+    protected final Set<Long> electingFollowers = new HashSet<>();
     // VisibleForTesting
     protected boolean electionFinished = false;
 

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/Learner.java

@@ -133,7 +133,7 @@ public class Learner {
         LOG.info("{} = {}", LEARNER_CLOSE_SOCKET_ASYNC, closeSocketAsync);
     }
 
-    final ConcurrentHashMap<Long, ServerCnxn> pendingRevalidations = new ConcurrentHashMap<Long, ServerCnxn>();
+    final ConcurrentHashMap<Long, ServerCnxn> pendingRevalidations = new ConcurrentHashMap<>();
 
     public int getPendingRevalidationsCount() {
         return pendingRevalidations.size();

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/LearnerHandler.java

@@ -114,7 +114,7 @@ public class LearnerHandler extends ZooKeeperThread {
     /**
      * The packets to be sent to the learner
      */
-    final LinkedBlockingQueue<QuorumPacket> queuedPackets = new LinkedBlockingQueue<QuorumPacket>();
+    final LinkedBlockingQueue<QuorumPacket> queuedPackets = new LinkedBlockingQueue<>();
     private final AtomicLong queuedPacketsSize = new AtomicLong();
 
     protected final AtomicLong packetsReceived = new AtomicLong();

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/LearnerSessionTracker.java

@@ -54,7 +54,7 @@ public class LearnerSessionTracker extends UpgradeableSessionTracker {
 
     private final SessionExpirer expirer;
     // Touch table for the global sessions
-    private final AtomicReference<Map<Long, Integer>> touchTable = new AtomicReference<Map<Long, Integer>>();
+    private final AtomicReference<Map<Long, Integer>> touchTable = new AtomicReference<>();
     private final long serverId;
     private final AtomicLong nextSessionId = new AtomicLong();
 
@@ -62,7 +62,7 @@ public class LearnerSessionTracker extends UpgradeableSessionTracker {
 
     public LearnerSessionTracker(SessionExpirer expirer, ConcurrentMap<Long, Integer> sessionsWithTimeouts, int tickTime, long id, boolean localSessionsEnabled, ZooKeeperServerListener listener) {
         this.expirer = expirer;
-        this.touchTable.set(new ConcurrentHashMap<Long, Integer>());
+        this.touchTable.set(new ConcurrentHashMap<>());
         this.globalSessionsWithTimeouts = sessionsWithTimeouts;
         this.serverId = id;
         nextSessionId.set(SessionTrackerImpl.initializeNextSessionId(serverId));
@@ -150,7 +150,7 @@ public class LearnerSessionTracker extends UpgradeableSessionTracker {
     }
 
     public Map<Long, Integer> snapshot() {
-        return touchTable.getAndSet(new ConcurrentHashMap<Long, Integer>());
+        return touchTable.getAndSet(new ConcurrentHashMap<>());
     }
 
     public long createSession(int sessionTimeout) {
@@ -202,7 +202,7 @@ public class LearnerSessionTracker extends UpgradeableSessionTracker {
         pwriter.print("Global Sessions(");
         pwriter.print(globalSessionsWithTimeouts.size());
         pwriter.println("):");
-        SortedSet<Long> sessionIds = new TreeSet<Long>(globalSessionsWithTimeouts.keySet());
+        SortedSet<Long> sessionIds = new TreeSet<>(globalSessionsWithTimeouts.keySet());
         for (long sessionId : sessionIds) {
             pwriter.print("0x");
             pwriter.print(Long.toHexString(sessionId));
@@ -222,7 +222,7 @@ public class LearnerSessionTracker extends UpgradeableSessionTracker {
 
     @Override
     public Map<Long, Set<Long>> getSessionExpiryMap() {
-        return new HashMap<Long, Set<Long>>();
+        return new HashMap<>();
     }
 
     public Set<Long> globalSessions() {

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/ObserverMaster.java

@@ -74,7 +74,7 @@ public class ObserverMaster extends LearnerMaster implements Runnable {
     private FollowerZooKeeperServer zks;
     private int port;
 
-    private Set<LearnerHandler> activeObservers = Collections.newSetFromMap(new ConcurrentHashMap<LearnerHandler, Boolean>());
+    private Set<LearnerHandler> activeObservers = Collections.newSetFromMap(new ConcurrentHashMap<>());
 
     private final ConcurrentHashMap<LearnerHandler, LearnerHandlerBean> connectionBeans = new ConcurrentHashMap<>();
 

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/ObserverRequestProcessor.java

@@ -45,7 +45,7 @@ public class ObserverRequestProcessor extends ZooKeeperCriticalThread implements
 
     // We keep a queue of requests. As requests get submitted they are
     // stored here. The queue is drained in the run() method.
-    LinkedBlockingQueue<Request> queuedRequests = new LinkedBlockingQueue<Request>();
+    LinkedBlockingQueue<Request> queuedRequests = new LinkedBlockingQueue<>();
 
     boolean finished = false;
 

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/ObserverZooKeeperServer.java

@@ -48,7 +48,7 @@ public class ObserverZooKeeperServer extends LearnerZooKeeperServer {
 
     /*
      * Pending sync requests
-     */ ConcurrentLinkedQueue<Request> pendingSyncs = new ConcurrentLinkedQueue<Request>();
+     */ ConcurrentLinkedQueue<Request> pendingSyncs = new ConcurrentLinkedQueue<>();
 
     ObserverZooKeeperServer(FileTxnSnapLog logFactory, QuorumPeer self, ZKDatabase zkDb) throws IOException {
         super(logFactory, self.tickTime, self.minSessionTimeout, self.maxSessionTimeout, self.clientPortListenBacklog, zkDb, self);

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/QuorumPeer.java

@@ -889,7 +889,7 @@ public class QuorumPeer extends ZooKeeperThread implements QuorumStats.Provider
 
     private AtomicReference<ZabState> zabState = new AtomicReference<>(ZabState.ELECTION);
     private AtomicReference<SyncMode> syncMode = new AtomicReference<>(SyncMode.NONE);
-    private AtomicReference<String> leaderAddress = new AtomicReference<String>("");
+    private AtomicReference<String> leaderAddress = new AtomicReference<>("");
     private AtomicLong leaderId = new AtomicLong(-1);
 
     private boolean reconfigFlag = false; // indicates that a reconfig just committed
@@ -1066,7 +1066,7 @@ public class QuorumPeer extends ZooKeeperThread implements QuorumStats.Provider
     public QuorumPeer() throws SaslException {
         super("QuorumPeer");
         quorumStats = new QuorumStats(this);
-        jmxRemotePeerBean = new HashMap<Long, RemotePeerBean>();
+        jmxRemotePeerBean = new HashMap<>();
         adminServer = AdminServerFactory.createAdminServer();
         x509Util = createX509Util();
         initialize();
@@ -1108,7 +1108,7 @@ public class QuorumPeer extends ZooKeeperThread implements QuorumStats.Provider
     public void initialize() throws SaslException {
         // init quorum auth server & learner
         if (isQuorumSaslAuthEnabled()) {
-            Set<String> authzHosts = new HashSet<String>();
+            Set<String> authzHosts = new HashSet<>();
             for (QuorumServer qs : getView().values()) {
                 authzHosts.add(qs.hostname);
             }
@@ -1660,7 +1660,7 @@ public class QuorumPeer extends ZooKeeperThread implements QuorumStats.Provider
     }
 
     public synchronized Set<Long> getCurrentAndNextConfigVoters() {
-        Set<Long> voterIds = new HashSet<Long>(getQuorumVerifier().getVotingMembers().keySet());
+        Set<Long> voterIds = new HashSet<>(getQuorumVerifier().getVotingMembers().keySet());
         if (getLastSeenQuorumVerifier() != null) {
             voterIds.addAll(getLastSeenQuorumVerifier().getVotingMembers().keySet());
         }
@@ -1680,7 +1680,7 @@ public class QuorumPeer extends ZooKeeperThread implements QuorumStats.Provider
      * Only used by QuorumStats at the moment
      */
     public String[] getQuorumPeers() {
-        List<String> l = new ArrayList<String>();
+        List<String> l = new ArrayList<>();
         synchronized (this) {
             if (leader != null) {
                 for (LearnerHandler fh : leader.getLearners()) {
@@ -2306,14 +2306,14 @@ public class QuorumPeer extends ZooKeeperThread implements QuorumStats.Provider
     }
 
     private void updateRemotePeerMXBeans(Map<Long, QuorumServer> newMembers) {
-        Set<Long> existingMembers = new HashSet<Long>(newMembers.keySet());
+        Set<Long> existingMembers = new HashSet<>(newMembers.keySet());
         existingMembers.retainAll(jmxRemotePeerBean.keySet());
         for (Long id : existingMembers) {
             RemotePeerBean rBean = jmxRemotePeerBean.get(id);
             rBean.setQuorumServer(newMembers.get(id));
         }
 
-        Set<Long> joiningMembers = new HashSet<Long>(newMembers.keySet());
+        Set<Long> joiningMembers = new HashSet<>(newMembers.keySet());
         joiningMembers.removeAll(jmxRemotePeerBean.keySet());
         joiningMembers.remove(getMyId()); // remove self as it is local bean
         for (Long id : joiningMembers) {
@@ -2327,7 +2327,7 @@ public class QuorumPeer extends ZooKeeperThread implements QuorumStats.Provider
             }
         }
 
-        Set<Long> leavingMembers = new HashSet<Long>(jmxRemotePeerBean.keySet());
+        Set<Long> leavingMembers = new HashSet<>(jmxRemotePeerBean.keySet());
         leavingMembers.removeAll(newMembers.keySet());
         for (Long id : leavingMembers) {
             RemotePeerBean rBean = jmxRemotePeerBean.remove(id);

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/QuorumPeerConfig.java

@@ -547,7 +547,7 @@ public class QuorumPeerConfig {
                 Properties cfg = new Properties();
                 cfg.load(new StringReader(qv.toString()));
 
-                List<String> servers = new ArrayList<String>();
+                List<String> servers = new ArrayList<>();
                 for (Entry<Object, Object> entry : cfg.entrySet()) {
                     String key = entry.getKey().toString().trim();
                     if (!needKeepVersion && key.startsWith("version")) {

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/ReadOnlyRequestProcessor.java

@@ -41,7 +41,7 @@ public class ReadOnlyRequestProcessor extends ZooKeeperCriticalThread implements
 
     private static final Logger LOG = LoggerFactory.getLogger(ReadOnlyRequestProcessor.class);
 
-    private final LinkedBlockingQueue<Request> queuedRequests = new LinkedBlockingQueue<Request>();
+    private final LinkedBlockingQueue<Request> queuedRequests = new LinkedBlockingQueue<>();
 
     private volatile boolean finished = false;
 

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/SyncedLearnerTracker.java

@@ -24,7 +24,7 @@ import org.apache.zookeeper.server.quorum.flexible.QuorumVerifier;
 
 public class SyncedLearnerTracker {
 
-    protected ArrayList<QuorumVerifierAcksetPair> qvAcksetPairs = new ArrayList<QuorumVerifierAcksetPair>();
+    protected ArrayList<QuorumVerifierAcksetPair> qvAcksetPairs = new ArrayList<>();
 
     public void addQuorumVerifier(QuorumVerifier qv) {
         qvAcksetPairs.add(new QuorumVerifierAcksetPair(qv, new HashSet<Long>(qv.getVotingMembers().size())));

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/UpgradeableSessionTracker.java

@@ -44,9 +44,9 @@ public abstract class UpgradeableSessionTracker implements SessionTracker {
     }
 
     public void createLocalSessionTracker(SessionExpirer expirer, int tickTime, long id, ZooKeeperServerListener listener) {
-        this.localSessionsWithTimeouts = new ConcurrentHashMap<Long, Integer>();
+        this.localSessionsWithTimeouts = new ConcurrentHashMap<>();
         this.localSessionTracker = new LocalSessionTracker(expirer, this.localSessionsWithTimeouts, tickTime, id, listener);
-        this.upgradingSessions = new ConcurrentHashMap<Long, Integer>();
+        this.upgradingSessions = new ConcurrentHashMap<>();
     }
 
     public boolean isTrackingSession(long sessionId) {

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/flexible/QuorumHierarchical.java

@@ -66,15 +66,15 @@ public class QuorumHierarchical implements QuorumVerifier {
 
     private static final Logger LOG = LoggerFactory.getLogger(QuorumHierarchical.class);
 
-    private HashMap<Long, Long> serverWeight = new HashMap<Long, Long>();
-    private HashMap<Long, Long> serverGroup = new HashMap<Long, Long>();
-    private HashMap<Long, Long> groupWeight = new HashMap<Long, Long>();
+    private HashMap<Long, Long> serverWeight = new HashMap<>();
+    private HashMap<Long, Long> serverGroup = new HashMap<>();
+    private HashMap<Long, Long> groupWeight = new HashMap<>();
 
     private int numGroups = 0;
 
-    private Map<Long, QuorumServer> allMembers = new HashMap<Long, QuorumServer>();
-    private Map<Long, QuorumServer> participatingMembers = new HashMap<Long, QuorumServer>();
-    private Map<Long, QuorumServer> observingMembers = new HashMap<Long, QuorumServer>();
+    private Map<Long, QuorumServer> allMembers = new HashMap<>();
+    private Map<Long, QuorumServer> participatingMembers = new HashMap<>();
+    private Map<Long, QuorumServer> observingMembers = new HashMap<>();
 
     private long version = 0;
 
@@ -255,7 +255,7 @@ public class QuorumHierarchical implements QuorumVerifier {
             sw.append('\n');
         }
 
-        Map<Long, String> groups = new HashMap<Long, String>();
+        Map<Long, String> groups = new HashMap<>();
         for (Entry<Long, Long> pair : serverGroup.entrySet()) {
             Long sid = pair.getKey();
             Long gid = pair.getValue();
@@ -326,7 +326,7 @@ public class QuorumHierarchical implements QuorumVerifier {
      * Verifies if a given set is a quorum.
      */
     public boolean containsQuorum(Set<Long> set) {
-        HashMap<Long, Long> expansion = new HashMap<Long, Long>();
+        HashMap<Long, Long> expansion = new HashMap<>();
 
         /*
          * Adds up weights per group

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/flexible/QuorumMaj.java

@@ -38,9 +38,9 @@ public class QuorumMaj implements QuorumVerifier {
 
     private static final Logger LOG = LoggerFactory.getLogger(QuorumMaj.class);
 
-    private Map<Long, QuorumServer> allMembers = new HashMap<Long, QuorumServer>();
-    private Map<Long, QuorumServer> votingMembers = new HashMap<Long, QuorumServer>();
-    private Map<Long, QuorumServer> observingMembers = new HashMap<Long, QuorumServer>();
+    private Map<Long, QuorumServer> allMembers = new HashMap<>();
+    private Map<Long, QuorumServer> votingMembers = new HashMap<>();
+    private Map<Long, QuorumServer> observingMembers = new HashMap<>();
     private long version = 0;
     protected int half;
 

zookeeper-server/src/main/java/org/apache/zookeeper/server/util/BitHashSet.java

@@ -53,7 +53,7 @@ public class BitHashSet implements Iterable<Integer> {
      * HashSet we need to go through all the words before return that
      * element, which is not efficient.
      */
-    private final Set<Integer> cache = new HashSet<Integer>();
+    private final Set<Integer> cache = new HashSet<>();
 
     private final int cacheSize;
 

zookeeper-server/src/main/java/org/apache/zookeeper/server/util/BitMap.java

@@ -30,8 +30,8 @@ import java.util.concurrent.locks.ReentrantReadWriteLock;
  */
 public class BitMap<T> {
 
-    private final Map<T, Integer> value2Bit = new HashMap<T, Integer>();
-    private final Map<Integer, T> bit2Value = new HashMap<Integer, T>();
+    private final Map<T, Integer> value2Bit = new HashMap<>();
+    private final Map<Integer, T> bit2Value = new HashMap<>();
 
     private final BitSet freedBitSet = new BitSet();
     private Integer nextBit = Integer.valueOf(0);

zookeeper-server/src/main/java/org/apache/zookeeper/server/util/SerializeUtils.java

@@ -162,7 +162,7 @@ public class SerializeUtils {
     }
 
     public static void serializeSnapshot(DataTree dt, OutputArchive oa, Map<Long, Integer> sessions) throws IOException {
-        HashMap<Long, Integer> sessSnap = new HashMap<Long, Integer>(sessions);
+        HashMap<Long, Integer> sessSnap = new HashMap<>(sessions);
         oa.writeInt(sessSnap.size(), "count");
         for (Entry<Long, Integer> entry : sessSnap.entrySet()) {
             oa.writeLong(entry.getKey().longValue(), "id");

zookeeper-server/src/main/java/org/apache/zookeeper/server/watch/WatchManagerOptimized.java

@@ -55,10 +55,10 @@ public class WatchManagerOptimized implements IWatchManager, IDeadWatcherListene
 
     private static final Logger LOG = LoggerFactory.getLogger(WatchManagerOptimized.class);
 
-    private final ConcurrentHashMap<String, BitHashSet> pathWatches = new ConcurrentHashMap<String, BitHashSet>();
+    private final ConcurrentHashMap<String, BitHashSet> pathWatches = new ConcurrentHashMap<>();
 
     // watcher to bit id mapping
-    private final BitMap<Watcher> watcherBitIdMap = new BitMap<Watcher>();
+    private final BitMap<Watcher> watcherBitIdMap = new BitMap<>();
 
     // used to lazily remove the dead watchers
     private final WatcherCleaner watcherCleaner;
@@ -304,10 +304,10 @@ public class WatchManagerOptimized implements IWatchManager, IDeadWatcherListene
 
     @Override
     public WatchesReport getWatches() {
-        Map<Long, Set<String>> id2paths = new HashMap<Long, Set<String>>();
+        Map<Long, Set<String>> id2paths = new HashMap<>();
         for (Entry<Watcher, Set<String>> e : getWatcher2PathesMap().entrySet()) {
             Long id = ((ServerCnxn) e.getKey()).getSessionId();
-            Set<String> paths = new HashSet<String>(e.getValue());
+            Set<String> paths = new HashSet<>(e.getValue());
             id2paths.put(id, paths);
         }
         return new WatchesReport(id2paths);
@@ -321,11 +321,11 @@ public class WatchManagerOptimized implements IWatchManager, IDeadWatcherListene
      */
     @Override
     public WatchesPathReport getWatchesByPath() {
-        Map<String, Set<Long>> path2ids = new HashMap<String, Set<Long>>();
+        Map<String, Set<Long>> path2ids = new HashMap<>();
         for (Entry<String, BitHashSet> e : pathWatches.entrySet()) {
             BitHashSet watchers = e.getValue();
             synchronized (watchers) {
-                Set<Long> ids = new HashSet<Long>(watchers.size());
+                Set<Long> ids = new HashSet<>(watchers.size());
                 path2ids.put(e.getKey(), ids);
                 for (Integer wbit : watchers) {
                     Watcher watcher = watcherBitIdMap.get(wbit);
@@ -343,7 +343,7 @@ public class WatchManagerOptimized implements IWatchManager, IDeadWatcherListene
      * it in this class.
      */
     public Map<Watcher, Set<String>> getWatcher2PathesMap() {
-        Map<Watcher, Set<String>> watcher2paths = new HashMap<Watcher, Set<String>>();
+        Map<Watcher, Set<String>> watcher2paths = new HashMap<>();
         for (Entry<String, BitHashSet> e : pathWatches.entrySet()) {
             String path = e.getKey();
             BitHashSet watchers = e.getValue();
@@ -355,7 +355,7 @@ public class WatchManagerOptimized implements IWatchManager, IDeadWatcherListene
                         continue;
                     }
                     if (!watcher2paths.containsKey(w)) {
-                        watcher2paths.put(w, new HashSet<String>());
+                        watcher2paths.put(w, new HashSet<>());
                     }
                     watcher2paths.get(w).add(path);
                 }

zookeeper-server/src/main/java/org/apache/zookeeper/server/watch/WatcherCleaner.java

@@ -80,7 +80,7 @@ public class WatcherCleaner extends Thread {
                 maxInProcessingDeadWatchers);
         }
         this.maxInProcessingDeadWatchers = maxInProcessingDeadWatchers;
-        this.deadWatchers = new HashSet<Integer>();
+        this.deadWatchers = new HashSet<>();
         this.cleaners = new WorkerService("DeadWatcherCleanner", watcherCleanThreadsNum, false);
 
         LOG.info(
@@ -151,7 +151,7 @@ public class WatcherCleaner extends Thread {
                 // there are millions of watches, that's why we're doing lazily
                 // batch clean up in a separate thread with a snapshot of the
                 // current dead watchers.
-                final Set<Integer> snapshot = new HashSet<Integer>(deadWatchers);
+                final Set<Integer> snapshot = new HashSet<>(deadWatchers);
                 deadWatchers.clear();
                 int total = snapshot.size();
                 LOG.info("Processing {} dead watchers", total);

zookeeper-server/src/main/java/org/apache/zookeeper/server/watch/WatchesPathReport.java

@@ -42,9 +42,9 @@ public class WatchesPathReport {
     }
 
     private static Map<String, Set<Long>> deepCopy(Map<String, Set<Long>> m) {
-        Map<String, Set<Long>> m2 = new HashMap<String, Set<Long>>();
+        Map<String, Set<Long>> m2 = new HashMap<>();
         for (Map.Entry<String, Set<Long>> e : m.entrySet()) {
-            m2.put(e.getKey(), new HashSet<Long>(e.getValue()));
+            m2.put(e.getKey(), new HashSet<>(e.getValue()));
         }
         return m2;
     }

zookeeper-server/src/main/java/org/apache/zookeeper/server/watch/WatchesReport.java

@@ -42,9 +42,9 @@ public class WatchesReport {
     }
 
     private static Map<Long, Set<String>> deepCopy(Map<Long, Set<String>> m) {
-        Map<Long, Set<String>> m2 = new HashMap<Long, Set<String>>();
+        Map<Long, Set<String>> m2 = new HashMap<>();
         for (Map.Entry<Long, Set<String>> e : m.entrySet()) {
-            m2.put(e.getKey(), new HashSet<String>(e.getValue()));
+            m2.put(e.getKey(), new HashSet<>(e.getValue()));
         }
         return m2;
     }

zookeeper-server/src/main/java/org/apache/zookeeper/server/watch/WatchesSummary.java

@@ -89,7 +89,7 @@ public class WatchesSummary {
      * @return map representation of summary
      */
     public Map<String, Object> toMap() {
-        Map<String, Object> summary = new LinkedHashMap<String, Object>();
+        Map<String, Object> summary = new LinkedHashMap<>();
         summary.put(KEY_NUM_CONNECTIONS, numConnections);
         summary.put(KEY_NUM_PATHS, numPaths);
         summary.put(KEY_NUM_TOTAL_WATCHES, totalWatches);

zookeeper-server/src/test/java/org/apache/zookeeper/GetEphemeralsTest.java

@@ -83,7 +83,7 @@ public class GetEphemeralsTest extends ClientBase {
     public void testGetEphemerals() throws IOException, KeeperException, InterruptedException {
 
         final CountDownLatch doneProcessing = new CountDownLatch(1);
-        final List<String> unexpectedBehavior = new ArrayList<String>();
+        final List<String> unexpectedBehavior = new ArrayList<>();
         zk.getEphemerals((rc, ctx, paths) -> {
             if (paths == null) {
                 unexpectedBehavior.add(String.format("Expected ephemeral count for"
@@ -112,7 +112,7 @@ public class GetEphemeralsTest extends ClientBase {
 
         final CountDownLatch doneProcessing = new CountDownLatch(1);
         final String checkPath = BASE + "0";
-        final List<String> unexpectedBehavior = new ArrayList<String>();
+        final List<String> unexpectedBehavior = new ArrayList<>();
         zk.getEphemerals(checkPath, (rc, ctx, paths) -> {
             if (paths == null) {
                 unexpectedBehavior.add(String.format("Expected ephemeral count for %s to be %d but was null", checkPath, expected.length));
@@ -141,7 +141,7 @@ public class GetEphemeralsTest extends ClientBase {
         final CountDownLatch doneProcessing = new CountDownLatch(1);
         final String checkPath = "/unknownPath";
         final int expectedSize = 0;
-        final List<String> unexpectedBehavior = new ArrayList<String>();
+        final List<String> unexpectedBehavior = new ArrayList<>();
         zk.getEphemerals(checkPath, (rc, ctx, paths) -> {
             if (paths == null) {
                 unexpectedBehavior.add(String.format("Expected ephemeral count for %s to be %d but was null", checkPath, expectedSize));

zookeeper-server/src/test/java/org/apache/zookeeper/JaasConfiguration.java

@@ -35,7 +35,7 @@ import javax.security.auth.login.AppConfigurationEntry.LoginModuleControlFlag;
  */
 public class JaasConfiguration extends javax.security.auth.login.Configuration {
 
-    private final Map<String, AppConfigurationEntry[]> sections = new HashMap<String, AppConfigurationEntry[]>();
+    private final Map<String, AppConfigurationEntry[]> sections = new HashMap<>();
 
     public JaasConfiguration() {
     }
@@ -47,7 +47,7 @@ public class JaasConfiguration extends javax.security.auth.login.Configuration {
      * @param args login key/value args
      */
     public void addSection(String name, String loginModuleName, String... args) {
-        Map<String, String> conf = new HashMap<String, String>();
+        Map<String, String> conf = new HashMap<>();
         // loop through the args (must be key/value sequence)
         for (int i = 0; i < args.length - 1; i += 2) {
             conf.put(args[i], args[i + 1]);

zookeeper-server/src/test/java/org/apache/zookeeper/RemoveWatchesTest.java

@@ -481,7 +481,7 @@ public class RemoveWatchesTest extends ClientBase {
     @Timeout(value = 90)
     public void testManyPreNodeWatchers(boolean useAsync) throws Exception {
         int count = 50;
-        List<MyWatcher> wList = new ArrayList<MyWatcher>(count);
+        List<MyWatcher> wList = new ArrayList<>(count);
         MyWatcher w;
         String path = "/node";
         // Exists watcher
@@ -510,7 +510,7 @@ public class RemoveWatchesTest extends ClientBase {
     @Timeout(value = 90)
     public void testManyChildWatchers(boolean useAsync) throws Exception {
         int count = 50;
-        List<MyWatcher> wList = new ArrayList<MyWatcher>(count);
+        List<MyWatcher> wList = new ArrayList<>(count);
         MyWatcher w;
         String path = "/node";
 
@@ -546,7 +546,7 @@ public class RemoveWatchesTest extends ClientBase {
     @Timeout(value = 90)
     public void testManyDataWatchers(boolean useAsync) throws Exception {
         int count = 50;
-        List<MyWatcher> wList = new ArrayList<MyWatcher>(count);
+        List<MyWatcher> wList = new ArrayList<>(count);
         MyWatcher w;
         String path = "/node";
 
@@ -578,7 +578,7 @@ public class RemoveWatchesTest extends ClientBase {
     @Timeout(value = 90)
     public void testManyWatchersWhenNoConnection(boolean useAsync) throws Exception {
         int count = 3;
-        List<MyWatcher> wList = new ArrayList<MyWatcher>(count);
+        List<MyWatcher> wList = new ArrayList<>(count);
         MyWatcher w;
         String path = "/node";
 
@@ -990,7 +990,7 @@ public class RemoveWatchesTest extends ClientBase {
         private final String path;
         private String eventPath;
         private CountDownLatch latch;
-        private List<EventType> eventsAfterWatchRemoval = new ArrayList<EventType>();
+        private List<EventType> eventsAfterWatchRemoval = new ArrayList<>();
         MyWatcher(String path, int count) {
             this.path = path;
             latch = new CountDownLatch(count);

zookeeper-server/src/test/java/org/apache/zookeeper/SaslAuthTest.java

@@ -128,7 +128,7 @@ public class SaslAuthTest extends ClientBase {
     public void testValidSaslIds() throws Exception {
         ZooKeeper zk = createClient();
 
-        List<String> validIds = new ArrayList<String>();
+        List<String> validIds = new ArrayList<>();
         validIds.add("user");
         validIds.add("service/host.name.com");
         validIds.add("user@KERB.REALM");
@@ -136,7 +136,7 @@ public class SaslAuthTest extends ClientBase {
 
         int i = 0;
         for (String validId : validIds) {
-            List<ACL> aclList = new ArrayList<ACL>();
+            List<ACL> aclList = new ArrayList<>();
             ACL acl = new ACL(0, new Id("sasl", validId));
             aclList.add(acl);
             zk.create("/valid" + i, null, aclList, CreateMode.PERSISTENT);
@@ -148,13 +148,13 @@ public class SaslAuthTest extends ClientBase {
     public void testInvalidSaslIds() throws Exception {
         ZooKeeper zk = createClient();
 
-        List<String> invalidIds = new ArrayList<String>();
+        List<String> invalidIds = new ArrayList<>();
         invalidIds.add("user@KERB.REALM/server.com");
         invalidIds.add("user@KERB.REALM1@KERB.REALM2");
 
         int i = 0;
         for (String invalidId : invalidIds) {
-            List<ACL> aclList = new ArrayList<ACL>();
+            List<ACL> aclList = new ArrayList<>();
             try {
                 ACL acl = new ACL(0, new Id("sasl", invalidId));
                 aclList.add(acl);
@@ -253,4 +253,4 @@ public class SaslAuthTest extends ClientBase {
             }
         }
     }
-}
+}

zookeeper-server/src/test/java/org/apache/zookeeper/ZooKeeperTest.java

@@ -550,7 +550,7 @@ public class ZooKeeperTest extends ClientBase {
         LsCommand cmd = new LsCommand();
         cmd.setZk(zk);
         cmd.parse("ls /".split(" "));
-        List<String> expected = new ArrayList<String>();
+        List<String> expected = new ArrayList<>();
         expected.add("[aa1, aa2, aa3, test1, zk1, zookeeper]");
         runCommandExpect(cmd, expected);
     }
@@ -571,7 +571,7 @@ public class ZooKeeperTest extends ClientBase {
         cmd.setZk(zk);
         cmd.parse("ls -R /a".split(" "));
 
-        List<String> expected = new ArrayList<String>();
+        List<String> expected = new ArrayList<>();
         expected.add("/a");
         expected.add("/a/b");
         expected.add("/a/c");
@@ -590,7 +590,7 @@ public class ZooKeeperTest extends ClientBase {
         cmd.setZk(zk);
         cmd.parse("ls -R /".split(" "));
 
-        List<String> expected = new ArrayList<String>();
+        List<String> expected = new ArrayList<>();
         expected.add("/");
         expected.add("/zookeeper");
         runCommandExpect(cmd, expected);
@@ -608,7 +608,7 @@ public class ZooKeeperTest extends ClientBase {
         cmd.setZk(zk);
         cmd.parse("ls -R /b/c".split(" "));
 
-        List<String> expected = new ArrayList<String>();
+        List<String> expected = new ArrayList<>();
         expected.add("/b/c");
         runCommandExpect(cmd, expected);
     }
@@ -626,7 +626,7 @@ public class ZooKeeperTest extends ClientBase {
         cmd.parse("ls -R /b/c/d".split(" "));
 
         try {
-            runCommandExpect(cmd, new ArrayList<String>());
+            runCommandExpect(cmd, new ArrayList<>());
             fail("Path doesn't exists so, command should fail.");
         } catch (CliWrapperException e) {
             assertEquals(KeeperException.Code.NONODE, ((KeeperException) e.getCause()).code());
@@ -691,7 +691,7 @@ public class ZooKeeperTest extends ClientBase {
         SyncCommand cmd = new SyncCommand();
         cmd.setZk(zk);
         cmd.parse("sync /".split(" "));
-        List<String> expected = new ArrayList<String>();
+        List<String> expected = new ArrayList<>();
         expected.add("Sync is OK");
 
         runCommandExpect(cmd, expected);

zookeeper-server/src/test/java/org/apache/zookeeper/server/CRCTest.java

@@ -72,7 +72,7 @@ public class CRCTest extends ZKTestCase {
     /** return if checksum matches for a snapshot **/
     private boolean getCheckSum(FileSnap snap, File snapFile) throws IOException {
         DataTree dt = new DataTree();
-        Map<Long, Integer> sessions = new ConcurrentHashMap<Long, Integer>();
+        Map<Long, Integer> sessions = new ConcurrentHashMap<>();
         InputStream snapIS = new BufferedInputStream(new FileInputStream(snapFile));
         CheckedInputStream crcIn = new CheckedInputStream(snapIS, new Adler32());
         InputArchive ia = BinaryInputArchive.getArchive(crcIn);

zookeeper-server/src/test/java/org/apache/zookeeper/server/FinalRequestProcessorTest.java

@@ -50,7 +50,7 @@ import org.mockito.stubbing.Answer;
 
 public class FinalRequestProcessorTest {
 
-    private List<ACL> testACLs = new ArrayList<ACL>();
+    private List<ACL> testACLs = new ArrayList<>();
     private final Record[] responseRecord = new Record[1];
     private final ReplyHeader[] replyHeaders = new ReplyHeader[1];
 
@@ -119,7 +119,7 @@ public class FinalRequestProcessorTest {
     @Test
     public void testACLDigestHashHiding_UserCanRead() {
         // Arrange
-        List<Id> authInfo = new ArrayList<Id>();
+        List<Id> authInfo = new ArrayList<>();
         authInfo.add(new Id("digest", "otheruser:somesecrethash"));
 
         // Act
@@ -133,7 +133,7 @@ public class FinalRequestProcessorTest {
     @Test
     public void testACLDigestHashHiding_UserCanAll() {
         // Arrange
-        List<Id> authInfo = new ArrayList<Id>();
+        List<Id> authInfo = new ArrayList<>();
         authInfo.add(new Id("digest", "user:secrethash"));
 
         // Act
@@ -147,7 +147,7 @@ public class FinalRequestProcessorTest {
     @Test
     public void testACLDigestHashHiding_AdminUser() {
         // Arrange
-        List<Id> authInfo = new ArrayList<Id>();
+        List<Id> authInfo = new ArrayList<>();
         authInfo.add(new Id("digest", "adminuser:adminsecret"));
 
         // Act
@@ -163,7 +163,7 @@ public class FinalRequestProcessorTest {
         // Arrange
         testACLs.clear();
         testACLs.addAll(Arrays.asList(new ACL(ZooDefs.Perms.READ, new Id("digest", "user:secrethash")), new ACL(ZooDefs.Perms.ADMIN, new Id("digest", "adminuser:adminsecret"))));
-        List<Id> authInfo = new ArrayList<Id>();
+        List<Id> authInfo = new ArrayList<>();
         authInfo.add(new Id("digest", "adminuser:adminsecret"));
 
         // Act

zookeeper-server/src/test/java/org/apache/zookeeper/server/PrepRequestProcessorTest.java

@@ -371,7 +371,7 @@ public class PrepRequestProcessorTest extends ClientBase {
         }
         @Override
         public Map<Long, Set<Long>> getSessionExpiryMap() {
-            return new HashMap<Long, Set<Long>>();
+            return new HashMap<>();
         }
         @Override
         public long getLocalSessionCount() {

zookeeper-server/src/test/java/org/apache/zookeeper/server/PurgeTxnTest.java

@@ -186,7 +186,7 @@ public class PurgeTxnTest extends ZKTestCase {
         List<File> foundSnaps = txnLog.findNValidSnapshots(1);
         assertEquals(0, foundSnaps.size());
 
-        List<File> expectedNRecentSnapFiles = new ArrayList<File>();
+        List<File> expectedNRecentSnapFiles = new ArrayList<>();
         int counter = offset + (2 * nRecentCount);
         for (int i = 0; i < nRecentCount; i++) {
             // simulate log file
@@ -234,12 +234,12 @@ public class PurgeTxnTest extends ZKTestCase {
         AtomicInteger offset = new AtomicInteger(0);
         File version2 = new File(tmpDir.toString(), "version-2");
         assertTrue(version2.mkdir(), "Failed to create version_2 dir:" + version2.toString());
-        List<File> snapsToPurge = new ArrayList<File>();
-        List<File> logsToPurge = new ArrayList<File>();
-        List<File> snaps = new ArrayList<File>();
-        List<File> logs = new ArrayList<File>();
-        List<File> snapsAboveRecentFiles = new ArrayList<File>();
-        List<File> logsAboveRecentFiles = new ArrayList<File>();
+        List<File> snapsToPurge = new ArrayList<>();
+        List<File> logsToPurge = new ArrayList<>();
+        List<File> snaps = new ArrayList<>();
+        List<File> logs = new ArrayList<>();
+        List<File> snapsAboveRecentFiles = new ArrayList<>();
+        List<File> logsAboveRecentFiles = new ArrayList<>();
         createDataDirFiles(offset, fileToPurgeCount, false, version2, snapsToPurge, logsToPurge);
         createDataDirFiles(offset, nRecentCount, false, version2, snaps, logs);
         logs.add(logsToPurge.remove(0)); // log that precedes first retained snapshot is also retained
@@ -285,8 +285,8 @@ public class PurgeTxnTest extends ZKTestCase {
         AtomicInteger offset = new AtomicInteger(0);
         File version2 = new File(tmpDir.toString(), "version-2");
         assertTrue(version2.mkdir(), "Failed to create version_2 dir:" + version2.toString());
-        List<File> snaps = new ArrayList<File>();
-        List<File> logs = new ArrayList<File>();
+        List<File> snaps = new ArrayList<>();
+        List<File> logs = new ArrayList<>();
         createDataDirFiles(offset, nRecentCount, testWithPrecedingLogFile, version2, snaps, logs);
 
         FileTxnSnapLog txnLog = new FileTxnSnapLog(tmpDir, tmpDir);
@@ -307,10 +307,10 @@ public class PurgeTxnTest extends ZKTestCase {
         AtomicInteger offset = new AtomicInteger(0);
         File version2 = new File(tmpDir.toString(), "version-2");
         assertTrue(version2.mkdir(), "Failed to create version_2 dir:" + version2.toString());
-        List<File> snapsToPurge = new ArrayList<File>();
-        List<File> logsToPurge = new ArrayList<File>();
-        List<File> snaps = new ArrayList<File>();
-        List<File> logs = new ArrayList<File>();
+        List<File> snapsToPurge = new ArrayList<>();
+        List<File> logsToPurge = new ArrayList<>();
+        List<File> snaps = new ArrayList<>();
+        List<File> logs = new ArrayList<>();
         createDataDirFiles(offset, fileToPurgeCount, false, version2, snapsToPurge, logsToPurge);
         createDataDirFiles(offset, nRecentCount, false, version2, snaps, logs);
         logs.add(logsToPurge.remove(0)); // log that precedes first retained snapshot is also retained
@@ -560,7 +560,7 @@ public class PurgeTxnTest extends ZKTestCase {
 
     private List<String> manyClientOps(final ZooKeeper zk, final CountDownLatch doPurge, int thCount, final String prefix) {
         Thread[] ths = new Thread[thCount];
-        final List<String> znodes = Collections.synchronizedList(new ArrayList<String>());
+        final List<String> znodes = Collections.synchronizedList(new ArrayList<>());
         final CountDownLatch finished = new CountDownLatch(thCount);
         final AtomicReference<Exception> exception = new AtomicReference<>();
         for (int indx = 0; indx < thCount; indx++) {

zookeeper-server/src/test/java/org/apache/zookeeper/server/ReferenceCountedACLCacheTest.java

@@ -50,14 +50,14 @@ public class ReferenceCountedACLCacheTest {
 
     @Test
     public void testWhetherOrderingMatters() {
-        List<ACL> testACL = new ArrayList<ACL>();
+        List<ACL> testACL = new ArrayList<>();
         testACL.add(new ACL(ZooDefs.Perms.READ, new Id("scheme", "ro")));
         testACL.add(new ACL(ZooDefs.Perms.WRITE, new Id("scheme", "rw")));
 
         ReferenceCountedACLCache cache = new ReferenceCountedACLCache();
         Long aclId = cache.convertAcls(testACL);
 
-        List<ACL> testACL2 = new ArrayList<ACL>();
+        List<ACL> testACL2 = new ArrayList<>();
         testACL2.add(new ACL(ZooDefs.Perms.WRITE, new Id("scheme", "rw")));
         testACL2.add(new ACL(ZooDefs.Perms.READ, new Id("scheme", "ro")));
 
@@ -279,7 +279,7 @@ public class ReferenceCountedACLCacheTest {
     }
 
     private List<ACL> createACL(String id) {
-        List<ACL> acl1 = new ArrayList<ACL>();
+        List<ACL> acl1 = new ArrayList<>();
         acl1.add(new ACL(ZooDefs.Perms.ADMIN, new Id("scheme", id)));
         return acl1;
     }

zookeeper-server/src/test/java/org/apache/zookeeper/server/SnapshotDigestTest.java

@@ -100,7 +100,7 @@ public class SnapshotDigestTest extends ClientBase {
         zk.delete(firstNode, -1);
 
         // trigger multi op
-        List<Op> subTxns = new ArrayList<Op>();
+        List<Op> subTxns = new ArrayList<>();
         for (int i = 0; i < 3; i++) {
             String path = pathPrefix + "-m" + i;
             subTxns.add(Op.create(path, path.getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT));

zookeeper-server/src/test/java/org/apache/zookeeper/server/TxnLogDigestTest.java

@@ -236,7 +236,7 @@ public class TxnLogDigestTest extends ClientBase {
         client.setData(path, updatedData.getBytes(), -1);
         nodes.put(path, updatedData);
 
-        List<Op> subTxns = new ArrayList<Op>();
+        List<Op> subTxns = new ArrayList<>();
         for (int i = 0; i < 3; i++) {
             path = prefix + "/m" + i;
             subTxns.add(Op.create(path, path.getBytes(),

zookeeper-server/src/test/java/org/apache/zookeeper/server/admin/CommandResponseTest.java

@@ -47,7 +47,7 @@ public class CommandResponseTest extends ZKTestCase {
     @Test
     public void testMap() {
         r.put("missing", "sudo");
-        Map<String, Object> m = new HashMap<String, Object>();
+        Map<String, Object> m = new HashMap<>();
         m.put("origin", "xkcd");
         m.put("url", "http://xkcd.com/149/");
         r.putAll(m);

zookeeper-server/src/test/java/org/apache/zookeeper/server/admin/CommandsTest.java

@@ -107,7 +107,7 @@ public class CommandsTest extends ClientBase {
     }
 
     public void testCommand(String cmdName, Field... fields) throws IOException, InterruptedException {
-        testCommand(cmdName, new HashMap<String, String>(), null, new HashMap<>(), HttpServletResponse.SC_OK, fields);
+        testCommand(cmdName, new HashMap<>(), null, new HashMap<>(), HttpServletResponse.SC_OK, fields);
     }
 
     private static class Field {
@@ -271,7 +271,7 @@ public class CommandsTest extends ClientBase {
 
     @Test
     public void testSetTraceMask() throws IOException, InterruptedException {
-        Map<String, String> kwargs = new HashMap<String, String>();
+        Map<String, String> kwargs = new HashMap<>();
         kwargs.put("traceMask", "1");
         testCommand("set_trace_mask", kwargs, null, new HashMap<>(), HttpServletResponse.SC_OK, new Field("tracemask", Long.class));
     }

zookeeper-server/src/test/java/org/apache/zookeeper/server/quorum/CnxManagerTest.java

@@ -78,7 +78,7 @@ public class CnxManagerTest extends ZKTestCase {
     public void setUp() throws Exception {
 
         this.count = 3;
-        this.peers = new HashMap<Long, QuorumServer>(count);
+        this.peers = new HashMap<>(count);
         peerTmpdir = new File[count];
         peerQuorumPort = new int[count];
         peerClientPort = new int[count];
@@ -499,7 +499,7 @@ public class CnxManagerTest extends ZKTestCase {
      */
     @Test
     public void testWorkerThreads() throws Exception {
-        ArrayList<QuorumPeer> peerList = new ArrayList<QuorumPeer>();
+        ArrayList<QuorumPeer> peerList = new ArrayList<>();
         try {
             for (int sid = 0; sid < 3; sid++) {
                 QuorumPeer peer = new QuorumPeer(peers, peerTmpdir[sid], peerTmpdir[sid], peerClientPort[sid], 3, sid, 1000, 2, 2, 2);

zookeeper-server/src/test/java/org/apache/zookeeper/server/quorum/CommitProcessorConcurrencyTest.java

@@ -63,7 +63,7 @@ public class CommitProcessorConcurrencyTest extends ZKTestCase {
 
     @BeforeEach
     public void setUp() throws Exception {
-        processedRequests = new LinkedBlockingQueue<Request>();
+        processedRequests = new LinkedBlockingQueue<>();
         processor = new MockCommitProcessor();
         CommitProcessor.setMaxReadBatchSize(-1);
         CommitProcessor.setMaxCommitBatchSize(1);
@@ -174,8 +174,8 @@ public class CommitProcessorConcurrencyTest extends ZKTestCase {
     @Test
     public void processAsMuchUncommittedRequestsAsPossibleTest() throws Exception {
         final String path = "/testAsMuchAsPossible";
-        List<Request> shouldBeProcessed = new LinkedList<Request>();
-        Set<Request> shouldNotBeProcessed = new HashSet<Request>();
+        List<Request> shouldBeProcessed = new LinkedList<>();
+        Set<Request> shouldNotBeProcessed = new HashSet<>();
         for (int sessionId = 1; sessionId <= 5; ++sessionId) {
             for (int readReqId = 1; readReqId <= sessionId; ++readReqId) {
                 Request readReq = newRequest(new GetDataRequest(path, false), OpCode.getData, sessionId, readReqId);
@@ -225,8 +225,8 @@ public class CommitProcessorConcurrencyTest extends ZKTestCase {
     @Test
     public void processAllFollowingUncommittedAfterFirstCommitTest() throws Exception {
         final String path = "/testUncommittedFollowingCommited";
-        Set<Request> shouldBeInPending = new HashSet<Request>();
-        Set<Request> shouldBeProcessedAfterPending = new HashSet<Request>();
+        Set<Request> shouldBeInPending = new HashSet<>();
+        Set<Request> shouldBeProcessedAfterPending = new HashSet<>();
 
         Request writeReq = newRequest(
             new CreateRequest(path, new byte[0], Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT_SEQUENTIAL.toFlag()),
@@ -287,7 +287,7 @@ public class CommitProcessorConcurrencyTest extends ZKTestCase {
     @Test
     public void processAllWritesMaxBatchSize() throws Exception {
         final String path = "/processAllWritesMaxBatchSize";
-        HashSet<Request> shouldBeProcessedAfterPending = new HashSet<Request>();
+        HashSet<Request> shouldBeProcessedAfterPending = new HashSet<>();
 
         Request writeReq = newRequest(
             new CreateRequest(
@@ -423,7 +423,7 @@ public class CommitProcessorConcurrencyTest extends ZKTestCase {
     public void noStarvationOfNonLocalCommittedRequestsTest() throws Exception {
         final String path = "/noStarvationOfCommittedRequests";
         processor.queuedRequests = new MockRequestsQueue();
-        Set<Request> nonLocalCommits = new HashSet<Request>();
+        Set<Request> nonLocalCommits = new HashSet<>();
         for (int i = 0; i < 10; i++) {
             Request nonLocalCommitReq = newRequest(
                 new CreateRequest(path, new byte[0], Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT_SEQUENTIAL.toFlag()),
@@ -461,7 +461,7 @@ public class CommitProcessorConcurrencyTest extends ZKTestCase {
         processor.queuedRequests.add(firstCommittedReq);
         processor.queuedWriteRequests.add(firstCommittedReq);
         processor.committedRequests.add(firstCommittedReq);
-        Set<Request> allReads = new HashSet<Request>();
+        Set<Request> allReads = new HashSet<>();
 
         // +1 read request to queuedRequests
         Request firstRead = newRequest(new GetDataRequest(path, false), OpCode.getData, 0x1, 0);
@@ -476,7 +476,7 @@ public class CommitProcessorConcurrencyTest extends ZKTestCase {
             2);
         processor.committedRequests.add(secondCommittedReq);
 
-        Set<Request> waitingCommittedRequests = new HashSet<Request>();
+        Set<Request> waitingCommittedRequests = new HashSet<>();
         // +99 non local committed requests
         for (int writeReqId = 3; writeReqId < 102; ++writeReqId) {
             Request writeReq = newRequest(
@@ -530,7 +530,7 @@ public class CommitProcessorConcurrencyTest extends ZKTestCase {
         final int firstCXid = 0x100;
         int readReqId = firstCXid;
         processor.stoppedMainLoop = true;
-        HashSet<Request> localRequests = new HashSet<Request>();
+        HashSet<Request> localRequests = new HashSet<>();
         // queue the blocking write request to queuedRequests
         Request firstCommittedReq = newRequest(
             new CreateRequest(path, new byte[0], Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT_SEQUENTIAL.toFlag()),
@@ -592,7 +592,7 @@ public class CommitProcessorConcurrencyTest extends ZKTestCase {
         final int numberofReads = 10;
         int readReqId = lastCXid;
         processor.stoppedMainLoop = true;
-        HashSet<Request> localRequests = new HashSet<Request>();
+        HashSet<Request> localRequests = new HashSet<>();
 
         // queue the blocking write request to queuedRequests
         Request orphanCommittedReq = newRequest(

zookeeper-server/src/test/java/org/apache/zookeeper/server/quorum/CommitProcessorTest.java

@@ -81,7 +81,7 @@ public class CommitProcessorTest extends ZKTestCase {
     boolean stopped;
     TestZooKeeperServer zks;
     File tmpDir;
-    ArrayList<TestClientThread> testClients = new ArrayList<TestClientThread>();
+    ArrayList<TestClientThread> testClients = new ArrayList<>();
     CommitProcessor commitProcessor;
 
     public void setUp(int numCommitThreads, int numClientThreads, int writePercent) throws Exception {
@@ -318,7 +318,7 @@ public class CommitProcessorTest extends ZKTestCase {
     private class MockProposalRequestProcessor extends Thread implements RequestProcessor {
 
         private final CommitProcessor commitProcessor;
-        private final LinkedBlockingQueue<Request> proposals = new LinkedBlockingQueue<Request>();
+        private final LinkedBlockingQueue<Request> proposals = new LinkedBlockingQueue<>();
 
         public MockProposalRequestProcessor(CommitProcessor commitProcessor) {
             this.commitProcessor = commitProcessor;
@@ -367,7 +367,7 @@ public class CommitProcessorTest extends ZKTestCase {
         RequestProcessor nextProcessor;
         CommitProcessor commitProcessor;
         AtomicLong expectedZxid = new AtomicLong(1);
-        ConcurrentHashMap<Long, AtomicInteger> cxidMap = new ConcurrentHashMap<Long, AtomicInteger>();
+        ConcurrentHashMap<Long, AtomicInteger> cxidMap = new ConcurrentHashMap<>();
 
         AtomicInteger outstandingReadRequests = new AtomicInteger(0);
         AtomicInteger outstandingWriteRequests = new AtomicInteger(0);

zookeeper-server/src/test/java/org/apache/zookeeper/server/quorum/FLEBackwardElectionRoundTest.java

@@ -49,7 +49,7 @@ public class FLEBackwardElectionRoundTest extends ZKTestCase {
     public void setUp() throws Exception {
         count = 3;
 
-        peers = new HashMap<Long, QuorumServer>(count);
+        peers = new HashMap<>(count);
         tmpdir = new File[count];
         port = new int[count];
         cnxManagers = new QuorumCnxManager[count - 1];