@AfterClass
  public static void tearDownAfterClass() {
    if (KDC != null) {
      KDC.stop();
    }
  }
Tests for HBASE-28321, where we have multiple server principals candidates for a rpc service.
<p>
Put here just because we need to visit some package private classes under this package.
hbase-server/src/test/java/org/apache/hadoop/hbase/ipc/TestMultipleServerPrincipalsIPC.java