src/vs/base/browser/ui/tree/asyncDataTree.ts/AsyncDataTreeNodeListDragAndDrop/onDragStart
class AsyncDataTreeNodeListDragAndDrop:	onDragStart(data: IDragAndDropData, originalEvent: DragEvent): void {
		if (this.dnd.onDragStart) {
			this.dnd.onDragStart(asAsyncDataTreeDragAndDropData(data), originalEvent);
		}
	}