ApiService

public interface ApiService {

    @Headers({"Accept: application/json"})
    @POST("/api/v1/mobile/participants")
    @FormUrlEncoded
    Call<JsonObject> register(@Field("first_name") String firstname,
                              @Field("last_name") String lastname,
                              @Field("phone_number") String phone_number,
                              @Field("project_code") String project_code,
                              @Field("app_version") String app_version,
                              @Field("fcm_key") String password,
                              @Field("phone_models") String password_confirmation,
                              @Field("device_type") String device_type,
                              @Field("device_hardware") String device_hardware,
                              @Field("device_manufacturer") String device_manufacturer);

}