svn merge -c 1551812 from trunk for HDFS-5674. Editlog code cleanup: remove @SuppressWarnings("deprecation") in FSEditLogOp; change FSEditLogOpCodes.fromByte(..) to be more efficient; and change Some fields in FSEditLog to final.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1551813 13f79535-47bb-0310-9956-ffa450edef68