@Test
  public void shutdownWithoutStartTest() throws InstantiationException, IOException {
    NioServer nioServer = getNettyServer(null);
    nioServer.shutdown();
  }
Tests for {@link NettyServer#shutdown()} when {@link NettyServer#start()} has not been called previously.
This test is for cases where {@link NettyServer#start()} has failed and {@link NettyServer#shutdown()} needs to be
run.
@throws InstantiationException
@throws IOException
ambry-rest/src/test/java/com/github/ambry/rest/NettyServerTest.java