src/vs/base/common/map.ts/ResourceMap/forEach
class ResourceMap:	forEach(clb: (value: T, key: URI, map: Map<URI, T>) => void, thisArg?: any): void {
		if (typeof thisArg !== 'undefined') {
			clb = clb.bind(thisArg);
		}
		for (const [_, entry] of this.map) {
			clb(entry.value, entry.uri, <any>this);
		}
	}