HADOOP-14958. Fix source-level compatibility after HADOOP-11252. Contributed by Junping Du.

(cherry picked from commit b016f08f67830ed3ca741bc6a10c3f5164781be5)
(cherry picked from commit 9433f9eb09af0ca61f01a2eb42ff3ffe31a94d5f)
(cherry picked from commit e7e2b8158d9aaf314698784d44f4dd9313df3b50)
(cherry picked from commit 4935334b0f0f04f2be5987ef124d1812a4dc844a)

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Client.java

@@ -213,7 +213,8 @@ public class Client implements AutoCloseable {
    * @param conf Configuration
    * @param pingInterval the ping interval
    */
-  static final void setPingInterval(Configuration conf, int pingInterval) {
+  public static final void setPingInterval(Configuration conf,
+      int pingInterval) {
     conf.setInt(CommonConfigurationKeys.IPC_PING_INTERVAL_KEY, pingInterval);
   }
 
@@ -224,7 +225,7 @@ public class Client implements AutoCloseable {
    * @param conf Configuration
    * @return the ping interval
    */
-  static final int getPingInterval(Configuration conf) {
+  public static final int getPingInterval(Configuration conf) {
     return conf.getInt(CommonConfigurationKeys.IPC_PING_INTERVAL_KEY,
         CommonConfigurationKeys.IPC_PING_INTERVAL_DEFAULT);
   }