public async Task <IActionResult> Desconto([FromServices] IVendaService service, [FromBody] DescontoRequest req) { var tsc = new TaskCompletionSource <IActionResult>(); try { service.DarDesconto(req.VendaId, req.Valor); tsc.SetResult(RetornoHelper.CreateResponse("OK", 200)); } catch (Exception e) { tsc.SetResult(RetornoHelper.CreateResponse(e.Message, 500)); } return(await tsc.Task); }