YARN-7698. A misleading variable's name in ApplicationAttemptEventDispatcher

Signed-off-by: Akira Ajisaka <aajisaka@apache.org>

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/ResourceManager.java

@@ -947,11 +947,11 @@ public class ResourceManager extends CompositeService implements Recoverable {
 
     @Override
     public void handle(RMAppAttemptEvent event) {
-      ApplicationAttemptId appAttemptID = event.getApplicationAttemptId();
-      ApplicationId appAttemptId = appAttemptID.getApplicationId();
-      RMApp rmApp = this.rmContext.getRMApps().get(appAttemptId);
+      ApplicationAttemptId appAttemptId = event.getApplicationAttemptId();
+      ApplicationId appId = appAttemptId.getApplicationId();
+      RMApp rmApp = this.rmContext.getRMApps().get(appId);
       if (rmApp != null) {
-        RMAppAttempt rmAppAttempt = rmApp.getRMAppAttempt(appAttemptID);
+        RMAppAttempt rmAppAttempt = rmApp.getRMAppAttempt(appAttemptId);
         if (rmAppAttempt != null) {
           try {
             rmAppAttempt.handle(event);