src/vs/workbench/api/common/extHostLanguageFeatures.ts/ExtHostLanguageFeatures/$provideTypeHierarchySubtypes
class ExtHostLanguageFeatures:	$provideTypeHierarchySubtypes(handle: number, sessionId: string, itemId: string, token: CancellationToken): Promise<extHostProtocol.ITypeHierarchyItemDto[] | undefined> {
		return this._withAdapter(handle, TypeHierarchyAdapter, adapter => adapter.provideSubtypes(sessionId, itemId, token), undefined, token);
	}