{
    if (that instanceof URLImageDescriptor)
    {
      URLImageDescriptor otherURLImageDescriptor = (URLImageDescriptor)that;
      return 
        url.equals(otherURLImageDescriptor.url) &&
          (key1 == null ? otherURLImageDescriptor.key1 == null : key1.equals(otherURLImageDescriptor.key1)) &&
          (key2 == null ? otherURLImageDescriptor.key2 == null : key2.equals(otherURLImageDescriptor.key2));
    }
    else
    {
      return false;
    }
  }