HADOOP-14986. Enforce JDK limitations.

(cherry picked from commit b50def36970e0afa65bd3fd3f40d8c4f81119200)
(cherry picked from commit 1660a638f04435ca363fe4f07c7f03f109a6784a)

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/metrics/util/MetricsRegistry.java

@@ -19,6 +19,7 @@ package org.apache.hadoop.metrics.util;
 
 import java.util.Collection;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 
@@ -33,7 +34,7 @@ import org.apache.hadoop.classification.InterfaceAudience;
 @Deprecated
 @InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
 public class MetricsRegistry {
-  private ConcurrentHashMap<String, MetricsBase> metricsList =
+  private ConcurrentMap<String, MetricsBase> metricsList =
       new ConcurrentHashMap<String, MetricsBase>();
 
   public MetricsRegistry() {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/top/window/RollingWindowManager.java

@@ -23,6 +23,7 @@ import java.util.Map;
 import java.util.Set;
 import java.util.Stack;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
@@ -141,7 +142,7 @@ public class RollingWindowManager {
    * maintains the set of {@link RollingWindow}s for the users that have
    * operated on that metric.
    */
-  public ConcurrentHashMap<String, RollingWindowMap> metricMap =
+  public ConcurrentMap<String, RollingWindowMap> metricMap =
       new ConcurrentHashMap<String, RollingWindowMap>();
 
   public RollingWindowManager(Configuration conf, int reportingPeriodMs) {

hadoop-project/pom.xml

@@ -1365,6 +1365,32 @@
             </goals>
           </execution>
         </executions>
+      </plugin>
+      <plugin>
+        <groupId>org.codehaus.mojo</groupId>
+        <artifactId>animal-sniffer-maven-plugin</artifactId>
+        <version>1.16</version>
+        <executions>
+          <execution>
+            <id>signature-check</id>
+            <phase>verify</phase>
+            <goals>
+              <goal>check</goal>
+            </goals>
+          </execution>
+        </executions>
+        <configuration>
+          <signature>
+            <groupId>org.codehaus.mojo.signature</groupId>
+            <artifactId>java17</artifactId>
+            <version>1.0</version>
+          </signature>
+          <ignores>
+            <ignore>sun.misc.*</ignore>
+            <ignore>sun.net.*</ignore>
+            <ignore>sun.nio.ch.*</ignore>
+          </ignores>
+        </configuration>
       </plugin>
        <plugin>
          <groupId>org.apache.maven.plugins</groupId>