if (location == null) throw new NullPointerException ();  if (context == null) throw new IllegalArgumentException ();  if (dropAction != DnDConstants.ACTION_NONE && dropAction != DnDConstants.ACTION_COPY && dropAction != DnDConstants.ACTION_MOVE && dropAction != DnDConstants.ACTION_COPY_OR_MOVE && dropAction != DnDConstants.ACTION_LINK && dropAction != DnDConstants.ACTION_REFERENCE) throw new IllegalArgumentException ();  int srcActionsMask = DnDConstants.ACTION_NONE | DnDConstants.ACTION_COPY | DnDConstants.ACTION_MOVE | DnDConstants.ACTION_COPY_OR_MOVE | DnDConstants.ACTION_LINK | DnDConstants.ACTION_REFERENCE;  if (~(srcActions ^ srcActionsMask) != 0) throw new IllegalArgumentException ();
  public DropTargetDragEvent (DropTargetContext context, Point location,                              int dropAction, int srcActions)  {    super (context);    this.dropAction = dropAction;    this.srcActions = srcActions;    this.location = location;  }