private void updateDeadServerRegionMetrics(int deadRegions, int unknownRegions) {
    metrics.updateDeadServerOpenRegions(deadRegions);
    metrics.updateUnknownServerOpenRegions(unknownRegions);
  }
Check that what the RegionServer reports aligns with the Master's image. If disagreement, we
will tell the RegionServer to expediently close a Region we do not think it should have.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/AssignmentManager.java