HDFS-5018. Merge change r1505603 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1505604 13f79535-47bb-0310-9956-ffa450edef68
svn merge -c 1505610 from trunk for HADOOP-9754. Remove unnecessary "throws IOException/InterruptedException", and fix generic and other javac warnings.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1505613 13f79535-47bb-0310-9956-ffa450edef68