@Override
          public Boolean evaluate() throws IOException {
            return !states.isRegionInTransition(region);
          }
Helper to synchronously wait on conditions. This will be removed in the future (mainly when the
AssignmentManager will be replaced with a Procedure version) by using ProcedureYieldException,
and the queue will handle waiting and scheduling based on events.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/procedure/ProcedureSyncWait.java