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
Merge remote branch 'origin/branch-2' into branch-2-gd
Merge remote branch 'origin/branch-2-gd' into fb-HADOOP-9315-branch-2-gd