@After
  public void tearDown() throws IOException {
    Closeables.close(rpcClient, true);
    rpcServer.stop();
  }
Test secure client connecting to a non secure server, where we have multiple server principal
candidates for a rpc service. See HBASE-28321.
hbase-server/src/test/java/org/apache/hadoop/hbase/security/TestMultipleServerPrincipalsFallbackToSimple.java