HDFS-5726. Fix compilation error in AbstractINodeDiff for JDK7. Contributed by Jing Zhao.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1556433 13f79535-47bb-0310-9956-ffa450edef68
YARN-1568. Rename clusterid to clusterId in ActiveRMInfoProto (kasha)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1556435 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-10208. Remove duplicate initialization in StringUtils.getStringCollection. Contributed by Benoy Antony.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1556602 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-10207. TestUserGroupInformation#testLogin is flaky (jxiang via cmccabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1556664 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-10214. Fix multithreaded correctness warnings in ActiveStandbyElector (Liang Xie via kasha)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1556734 13f79535-47bb-0310-9956-ffa450edef68
Merge remote-tracking branch 'apache/trunk' into YARN-1166
Add a test case for RM restart scenario, and incorporate Vinod's
comment.