Can't set body through ClientRequestFilter

Question

I'm developing a Quarkus app and trying to insert a body in a Post Request through intercepting it on a ClientRequestFilter. The method is exectuted on each call and the Entity changes correctly, but when I test this request (on Postman), the body is still the same Postman sent.

This is the method:

   public void filter(ClientRequestContext requestContext) throws IOException {
       if (requestContext.getMethod().equals("POST")) {
           UserDTO user = new UserDTO("aaa", "bbb");
           requestContext.setEntity(user);
       }
   } 

Thank you!