public boolean isMetaRegionInTransition() {
    return !isMetaAssigned();
  }
Notice that, this only means the meta region is available on a RS, but the AM may still be
loading the region states from meta, so usually you need to check {@link #isMetaLoaded()} first
before checking this method, unless you can make sure that your piece of code can only be
executed after AM builds the region states.
@see #isMetaLoaded()
hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/AssignmentManager.java