HDFS-15639. [JDK 11] Fix Javadoc errors in hadoop-hdfs-client. (#2394)

(cherry picked from commit 30f06e0c742806c7b9edf00a92c98b1e9cfcb0e1)

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/AbstractFileSystem.java

@@ -846,7 +846,8 @@ public abstract class AbstractFileSystem {
 
   /**
    * Synchronize client metadata state.
-   * <p/>In some FileSystem implementations such as HDFS metadata
+   * <p>
+   * In some FileSystem implementations such as HDFS metadata
    * synchronization is essential to guarantee consistency of read requests
    * particularly in HA setting.
    * @throws IOException

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileSystem.java

@@ -2568,7 +2568,8 @@ public abstract class FileSystem extends Configured
 
   /**
    * Synchronize client metadata state.
-   * <p/>In some FileSystem implementations such as HDFS metadata
+   * <p>
+   * In some FileSystem implementations such as HDFS metadata
    * synchronization is essential to guarantee consistency of read requests
    * particularly in HA setting.
    * @throws IOException

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/fs/Hdfs.java

@@ -156,7 +156,8 @@ public class Hdfs extends AbstractFileSystem {
 
   /**
    * Synchronize client metadata state with Active NameNode.
-   * <p/>In HA the client synchronizes its state with the Active NameNode
+   * <p>
+   * In HA the client synchronizes its state with the Active NameNode
    * in order to guarantee subsequent read consistency from Observer Nodes.
    * @throws IOException
    */

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DistributedFileSystem.java

@@ -1613,7 +1613,8 @@ public class DistributedFileSystem extends FileSystem
 
   /**
    * Synchronize client metadata state with Active NameNode.
-   * <p/>In HA the client synchronizes its state with the Active NameNode
+   * <p>
+   * In HA the client synchronizes its state with the Active NameNode
    * in order to guarantee subsequent read consistency from Observer Nodes.
    * @throws IOException
    */