Merge r1615025 from trunk: YARN-2051. Fix bug in PBimpls and add more unit tests with reflection. (Contributed by Binglin Chang)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1615027 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6798: Merging r1615044 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1615045 13f79535-47bb-0310-9956-ffa450edef68