(cherry picked from commit 3122daa80261b466e309e88d88d1e2c030525e3f) Conflicts: hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/rm/preemption/CheckpointAMPreemptionPolicy.java