private void regionOpenedWithoutPersistingToMeta(AssignmentManager am, RegionStateNode regionNode,
    TransitionCode transitionCode, long openSeqNum) throws IOException {
    if (openSeqNum < regionNode.getOpenSeqNum()) {
      LOG.warn(
        "Received report {} transition from {} for {}, pid={} but the new openSeqNum {}"
          + " is less than the current one {}, ignoring...",
        transitionCode, targetServer, regionNode, getProcId(), openSeqNum,
        regionNode.getOpenSeqNum());
    } else {
      regionNode.setOpenSeqNum(openSeqNum);
    }
    am.regionOpenedWithoutPersistingToMeta(regionNode);
  }
The remote procedure used to open a region.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/OpenRegionProcedure.java