As reported in RT-34484, the releaseCurrentDragboard() method can be called multiple times, causing an assertion to fail. Apparently, the method gets invoked from both ClipboardAssistance.actionPerformed() and GlassSceneDnDEventHandler.handleDragEnd(). Note that the latter is callback for Glass' View.notifyDragEnd() which seems to be invoked directly from native code on Mac and iOS only.

In any case, calling this method multiple times doesn't make any sense and should be eliminated. The event should be reported exactly once.