src/vs/workbench/api/common/extHostTypes.ts/DataTransfer/constructor
class DataTransfer:	constructor(init?: Iterable<readonly [string, DataTransferItem]>) {
		for (const [mime, item] of init ?? []) {
			const existing = this.#items.get(mime);
			if (existing) {
				existing.push(item);
			} else {
				this.#items.set(mime, [item]);
			}
		}
	}