@Test
  public void getNettyServerTest() throws Exception {
    Properties properties = new Properties();
    doGetNettyServerTest(properties, SSL_FACTORY);
    doGetNettyServerTest(properties, null);
    // test with ssl
    properties.setProperty("netty.server.enable.ssl", "true");
    doGetNettyServerTest(properties, SSL_FACTORY);
    // test overriding ssl factory
    File trustStoreFile = File.createTempFile("truststore", ".jks");
    trustStoreFile.deleteOnExit();
    TestSSLUtils.addSSLProperties(properties, "", SSLFactory.Mode.SERVER, trustStoreFile, "frontend");
    properties.setProperty(NettyConfig.SSL_FACTORY_KEY, NettySslFactory.class.getName());
    doGetNettyServerTest(properties, SSL_FACTORY);
  }
Checks to see that getting the default {@link NioServer} (currently {@link NettyServer}) works.
ambry-rest/src/test/java/com/github/ambry/rest/FrontendNettyFactoryTest.java