if (!(o instanceof Entry)) {
      return false;
    }
    return c.contains(unmodifiableEntry((Entry<?, ?>) o));
  }

  /**
   * Implements {@code Collection.remove} safely for forwarding collections of map entries. If
   * {@code o} is an instance of {@code Entry}, it is wrapped using {@link #unmodifiableEntry} to
   * protect against a possible nefarious equals method.
   *