@Override
      public void doWork() {
        ref.memberFinishedBarrier(opName, this.cohort[1], new byte[0]);
        ref.memberFinishedBarrier(opName, this.cohort[3], new byte[0]);
      }
Test that if nodes join the barrier early we still correctly handle the progress
hbase-server/src/test/java/org/apache/hadoop/hbase/procedure/TestProcedureCoordinator.java