public BufferCapabilities(ImageCapabilities front, ImageCapabilities back,
public BufferCapabilities(ImageCapabilities frontCaps, ImageCapabilities backCaps,
  public BufferCapabilities(ImageCapabilities front,			    ImageCapabilities back,                            FlipContents flip)  {    if (front ==  null || back == null)      throw new IllegalArgumentException();    this.front = front;    this.back = back;    this.flip = flip;  }