Example.java

@RequiredArgsConstructor(onConstructor = @__(@javax.inject.Inject))
public class Users {
  
    private final Client client;
  
    public GetUserRequest getUser(long userId) {
        return new GetUserRequest(client, userId);
    }
  
}

@Data
public class GetUserRequest {

    private final Client client;
    private final long userId;
    
    public Single<User> execute() {
        return client.get(Service.REST_API, "/users/" + userId);
    }

}