gistfile1.txt

    @Multipart
    @POST("test/register")
    Call<Result> registration(
                               @Part("email") String email,
                               @Part("password") String password,
                               @Part("firstname") String firstName,
                               @Part("lastname") String lastName,
                               @Part("gender") String gender,
                               @Part("birthday") String birthday,
                               @Part MultipartBody.Part filePart
                               );
                               
Call<Result> call = service.registration("borodachenko@gmail.com","passwordQ13" ,
                "Александр", "Симоненко", "male", "1990-11-27", filePart);