YARN-5400. addendum patch to fix JDK 7 issue

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

@@ -412,7 +412,8 @@ public class ZKRMStateStore extends RMStateStore {
             ReservationAllocationStateProto.parseFrom(reservationData);
 
         if (!rmState.getReservationState().containsKey(planName)) {
-          rmState.getReservationState().put(planName, new HashMap<>());
+          rmState.getReservationState().put(planName,
+              new HashMap<ReservationId, ReservationAllocationStateProto>());
         }
 
         ReservationId reservationId =