node.setOnDragDone ( event ->{
    System.out.println("Drag Done: "+event.getGestureSource() + ", "+event.getGestureTarget());
    // Output: Drag Done: draggedNode, null
    // Where draggedNode is custom node representing connection
    if (event.isAccepted()) {
        // handle success
    } else {
        // handle failure
    }
    event.consume();
});

node.setOnDragOver(event ->{
    System.out.println("Drag Over: "+event.getGestureSource() + ", "+event.getGestureTarget());
    // Output: DragOver: draggedNode, this node
    if (event.getGestureSource()  != this) {
        event.acceptTransferModes(TransferMode.COPY_OR_MOVE);
    }
    event.consume();
});