src/vs/workbench/api/common/extHostLanguageFeatures.ts/CodeActionAdapter/resolveCodeAction
class CodeActionAdapter:	async resolveCodeAction(id: extHostProtocol.ChainedCacheId, token: CancellationToken): Promise<extHostProtocol.IWorkspaceEditDto | undefined> {
		const [sessionId, itemId] = id;
		const item = this._cache.get(sessionId, itemId);
		if (!item || CodeActionAdapter._isCommand(item)) {
			return undefined; // code actions only!
		}
		if (!this._provider.resolveCodeAction) {
			return; // this should not happen...
		}
		const resolvedItem = (await this._provider.resolveCodeAction(item, token)) ?? item;
		return resolvedItem?.edit
			? typeConvert.WorkspaceEdit.from(resolvedItem.edit, undefined)
			: undefined;
	}