As @reamon indicated you can’t post a body with GET.
If you want to use GET provide the two inputs via query params
e.g.
/sumar?num1=1&num2=99
Then update your service to remove ‘request’ document wrapper and simply have num1 and num2 as your inputs to your service.
If you want to use a body, you will have to provide a POST based API.
regards
John.