private void postCompletedMergeRegions(final MasterProcedureEnv env) throws IOException {
    final MasterCoprocessorHost cpHost = env.getMasterCoprocessorHost();
    if (cpHost != null) {
      cpHost.postCompletedMergeRegionsAction(regionsToMerge, mergedRegion, getUser());
    }
  }
Post merge region action
@param env MasterProcedureEnv
hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/MergeTableRegionsProcedure.java