src/vs/workbench/api/common/extHostTreeViews.ts/ExtHostTreeView/onDrop
class ExtHostTreeView:	async onDrop(treeDataTransfer: vscode.DataTransfer, targetHandleOrNode: TreeItemHandle | undefined, token: CancellationToken): Promise<void> {
		const target = targetHandleOrNode ? this.getExtensionElement(targetHandleOrNode) : undefined;
		if ((!target && targetHandleOrNode) || !this.dndController?.handleDrop) {
			return;
		}
		return asPromise(() => this.dndController?.handleDrop
			? this.dndController.handleDrop(target, treeDataTransfer, token)
			: undefined);
	}