code: public static void checkSuperClass(Service s, Class<?> subClass,
              Class<?> superClass) throws NoSuchAlgorithmException {
          if (superClass == null) {
              return;
          }
          if (superClass.isAssignableFrom(subClass) == false) {
              throw new NoSuchAlgorithmException
                  ("class configured for " + s.getType() + ": "
                  + s.getClassName() + " not a " + s.getType());
          }
      }
docs: Check is subClass is a subclass of superClass. If not,
  throw a NoSuchAlgorithmException.