svn merge -c 1509070 from trunk for HADOOP-9803. Add a generic type parameter to RetryInvocationHandler.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1509071 13f79535-47bb-0310-9956-ffa450edef68
svn merge -c 1509075 from trunk for HDFS-4513. Clarify in the WebHDFS REST API that all JSON respsonses may contain additional properties.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1509076 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-2' into branch-2-gd
Merge remote branch 'origin/branch-2-gd' into fb-MAPREDUCE-4884-branch-2-gd