src/vs/workbench/api/common/extHostTreeViews.ts/ExtHostTreeView/onDrop
class ExtHostTreeView:	onDrop(treeItemHandleOrNodes: TreeItemHandle[], targetHandleOrNode: TreeItemHandle): Promise<void> {
		const elements = <T[]>treeItemHandleOrNodes.map(item => this.getExtensionElement(item)).filter(element => !isUndefinedOrNull(element));
		const target = this.getExtensionElement(targetHandleOrNode);
		if (elements && target) {
			return asPromise(() => this.dndController?.onDrop(elements, target));
		}
		return Promise.resolve(undefined);
	}