svn merge -c 1443257 FIXES: MAPREDUCE-4822. Unnecessary conversions in History Events. Contributed by Chu Tong


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1443269 13f79535-47bb-0310-9956-ffa450edef68
Merge branch 'branch-2' of github.com:griddynamics/yhadoop-common into branch-2-gd
Merge branch 'branch-2-gd' of github.com:griddynamics/yhadoop-common into fb-MAPREDUCE-4884-branch-2-gd