HBASE-26216 Move HRegionServer.abort(String) to Abortable as a default method (#3642)

Signed-off-by: Duo Zhang <zhangduo@apache.org>

hbase-client/src/main/java/org/apache/hadoop/hbase/Abortable.java

@@ -37,6 +37,16 @@ public interface Abortable {
    */
   void abort(String why, Throwable e);
 
+  /**
+   * It just call another abort method and the Throwable
+   * parameter is null.
+   * @param why Why we're aborting.
+   * @see Abortable#abort(String, Throwable)
+   */
+  default void abort(String why) {
+    abort(why, null);
+  }
+
   /**
    * Check if the server or client was aborted.
    * @return true if the server or client was aborted, false otherwise

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java

@@ -2647,13 +2647,6 @@ public class HRegionServer extends Thread implements
     return abortRequested.compareAndSet(false, true);
   }
 
-  /**
-   * @see HRegionServer#abort(String, Throwable)
-   */
-  public void abort(String reason) {
-    abort(reason, null);
-  }
-
   @Override
   public boolean isAborted() {
     return abortRequested.get();