Addendum of HDFS-8135.

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

@@ -25,7 +25,7 @@ import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.util.StringUtils;
 
 @InterfaceAudience.Private
-public final class HdfsConstants {
+public class HdfsConstants {
   // Long that indicates "leave current quota unchanged"
   public static final long QUOTA_DONT_SET = Long.MAX_VALUE;
   public static final long QUOTA_RESET = -1L;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/FSConstants.java

@@ -23,5 +23,5 @@ package org.apache.hadoop.hdfs.protocol;
  * it for SafemodeAction and DatanodeReport types.
  */
 @Deprecated
-public abstract class FSConstants extends HdfsConstants {
+public final class FSConstants extends HdfsConstants {
 }