code: public static <S> S loadFromSystemProperty(final Class<S> service) {
      try {
        final String className = System.getProperty(service.getName());
        if (className != null) {
          Class<?> c = ClassLoader.getSystemClassLoader().loadClass(className);
          return (S) c.newInstance();
        }
        return null;
      } catch (Exception e) {
        throw new Error(e);
      }
    }
docs: Internal API to support built-in SPIs that check a system property first.
  Returns an instance specified by a property with the class' binary name, or null if
  no such property is set.
  @hide