* https://github.com/typetools/checker-framework/issues/3030
       *
       * https://github.com/typetools/checker-framework/issues/3236
       */
      String key = (String) requireNonNull(e.nextElement());
      /*
       * requireNonNull is safe because the key came from propertyNames...
       *
       * ...except that it's possible for users to insert a string key with a non-string value, and

       * https://github.com/typetools/checker-framework/issues/3030
       *
       * https://github.com/typetools/checker-framework/issues/3236
       */
      String key = (String) requireNonNull(e.nextElement());
      /*
       * requireNonNull is safe because the key came from propertyNames...
       *
       * ...except that it's possible for users to insert a string key with a non-string value, and

     *            information along, may be <code>null</code>.
     */
    public void merge(Model target, Model source, boolean sourceDominant, Map<?, ?> hints) {
        Objects.requireNonNull(target, "target cannot be null");

        if (source == null) {
            return;
        }

        Map<Object, Object> context = new HashMap<>();
        if (hints != null) {