HDFS-14912. Set dfs.image.string-tables.expanded default to false in branch-2.7. Contributed by Siyao Meng.

Signed-off-by: Wei-Chiu Chuang <weichiu@apache.org>

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java

@@ -624,7 +624,7 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
   // String table in the fsimage utilizes an expanded bit range.
   public static final String DFS_IMAGE_EXPANDED_STRING_TABLES_KEY =
       "dfs.image.string-tables.expanded";
-  public static final boolean DFS_IMAGE_EXPANDED_STRING_TABLES_DEFAULT = true;
+  public static final boolean DFS_IMAGE_EXPANDED_STRING_TABLES_DEFAULT = false;
 
   // Image transfer timeout
   public static final String DFS_IMAGE_TRANSFER_TIMEOUT_KEY = "dfs.image.transfer.timeout";