YARN-4675. Reorganize TimelineClient and TimelineClientImpl into separate classes for ATSv1.x and ATSv2. Contributed by Naganarasimha G R.

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/jobhistory/JobHistoryEventHandler.java

@@ -79,8 +79,6 @@ import org.apache.hadoop.yarn.event.EventHandler;
 import org.apache.hadoop.yarn.exceptions.YarnException;
 import org.apache.hadoop.yarn.exceptions.YarnRuntimeException;
 import org.apache.hadoop.yarn.util.TimelineServiceHelper;
-import org.codehaus.jackson.map.ObjectMapper;
-import org.codehaus.jackson.node.JsonNodeFactory;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.sun.jersey.api.client.ClientHandlerException;