src/vs/workbench/api/common/extHostLanguageFeatures.ts/ReferenceAdapter/provideReferences
class ReferenceAdapter:	provideReferences(resource: URI, position: IPosition, context: modes.ReferenceContext, token: CancellationToken): Promise<modes.Location[] | undefined> {
		const doc = this._documents.getDocument(resource);
		const pos = typeConvert.Position.to(position);

		return asPromise(() => this._provider.provideReferences(doc, pos, context, token)).then(value => {
			if (Array.isArray(value)) {
				return value.map(typeConvert.location.from);
			}
			return undefined;
		});
	}