private void setMetaAssigned(RegionInfo metaRegionInfo, boolean assigned) {
    assert isMetaRegion(metaRegionInfo) : "unexpected non-meta region " + metaRegionInfo;
    ProcedureEvent<?> metaAssignEvent = getMetaAssignEvent(metaRegionInfo);
    if (assigned) {
      metaAssignEvent.wake(getProcedureScheduler());
    } else {
      metaAssignEvent.suspend();
    }
  }
Notice that this event does not mean the AM has already finished region state rebuilding. See
the comment of {@link #isMetaAssigned()} for more details.
@see #isMetaAssigned()
hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/AssignmentManager.java