private void updateCacheOfRSGroups(final Set<String> currentGroups) {
    this.prevRSGroups.clear();
    this.prevRSGroups.addAll(currentGroups);
  }
Update cache of rsgroups. Caller must be synchronized on 'this'.
@param currentGroups Current list of Groups.
hbase-server/src/main/java/org/apache/hadoop/hbase/rsgroup/RSGroupInfoManagerImpl.java