code: static public Class<? extends Standalone> resolveStandaloneClass() {
          return resolveStandaloneClass(
              System.getProperty(Standalone.KEY_NINJA_STANDALONE_CLASS),
              ForwardingServiceLoader.loadWithSystemServiceLoader(Standalone.class),
              Standalone.DEFAULT_STANDALONE_CLASS
          );
      }
docs: Resolves which standalone class to use. Either defined as a system
  property or falling back to the default.
  @return The resolved standalone class to use