@AfterClass
  public static void tearDownAfterClass() throws Exception {
    // make sure that we can stop the cluster cleanly
    UTIL.shutdownMiniCluster();
  }
Test to confirm that we will not hang when stop a backup master which is trying to become the
active master. See HBASE-19838
hbase-server/src/test/java/org/apache/hadoop/hbase/master/TestShutdownBackupMaster.java