private void preSplitRegionBeforeMETA(final MasterProcedureEnv env)
    throws IOException, InterruptedException {
    final List<Mutation> metaEntries = new ArrayList<Mutation>();
    final MasterCoprocessorHost cpHost = env.getMasterCoprocessorHost();
    if (cpHost != null) {
      cpHost.preSplitBeforeMETAAction(getSplitRow(), metaEntries, getUser());
      try {
        for (Mutation p : metaEntries) {
          RegionInfo.parseRegionName(p.getRow());
        }
      } catch (IOException e) {
        LOG.error("pid=" + getProcId() + " row key of mutation from coprocessor not parsable as "
          + "region name." + "Mutations from coprocessor should only for hbase:meta table.");
        throw e;
      }
    }
  }
Post split region actions before the Point-of-No-Return step
@param env MasterProcedureEnv
hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/SplitTableRegionProcedure.java