Send Mail basic implementation via MailGun API and Retrofit for Android

MailGunBasicSendMail.java

import android.util.Base64;

import com.google.gson.Gson;
import com.hpsaturn.robotsanta.Config;
import com.hpsaturn.robotsanta.models.MailGunResponse;

import retrofit.Callback;
import retrofit.RestAdapter;
import retrofit.converter.GsonConverter;
import retrofit.http.Field;
import retrofit.http.FormUrlEncoded;
import retrofit.http.Header;
import retrofit.http.Headers;
import retrofit.http.POST;

/**
 * Created by Antonio Vanegas @hpsaturn on 11/15/15.
 */
public class MailGun {

    private static final String TAG = MailGun.class.getSimpleName();
    private static final boolean DEBUG = Config.DEBUG;

    private static final String ENDPOINT = "https://api.mailgun.net/v3/yourdomain.com/";
    public static final String ACCEPT_JSON_HEADER = "Accept: application/json";
    public static final String BASIC = "Basic";

    private SendMailApi sendMailApi;

    public interface SendMailApi {

        @Headers({ACCEPT_JSON_HEADER})
        @FormUrlEncoded
        @POST("/messages")
        void authUser(
                @Header("Authorization") String authorizationHeader,
                @Field("from") String from,
                @Field("to") String to,
                @Field("subject") String subject,
                @Field("text") String text,
                Callback<MailGunResponse> cb
        );
    }

    public void sendMail(String to, String subject, String msg, Callback<MailGunResponse> cb){
        String from = "User Name Maybe <mailgun@yourdomain.com>";
        String clientIdAndSecret = "api" + ":" + "key-AdFEFtggxxxYourApiKey";
        String authorizationHeader = BASIC + " " + Base64.encodeToString(clientIdAndSecret.getBytes(), Base64.NO_WRAP);
        sendMailApi.authUser(authorizationHeader,from, to, subject, msg, cb);
    }

    public MailGun() {
        RestAdapter restAdapter = getAuthAdapter();
        sendMailApi = restAdapter.create(SendMailApi.class);
    }

    private RestAdapter getAuthAdapter(){
        RestAdapter.LogLevel logLevel = RestAdapter.LogLevel.NONE;
        if(DEBUG)logLevel = RestAdapter.LogLevel.FULL;
        return new RestAdapter.Builder()
                .setEndpoint(ENDPOINT)
                .setConverter(new GsonConverter(new Gson()))
                .setLogLevel(logLevel)
                .build();
    }
    
}

I'm struggling to find the gradle compile for 'com.hpsaturn.robotsanta'. Will someone please provide it?

can you provide this file com.hpsaturn.robotsanta.models.MailGunResponse

It should be fairly simple as Mailgun's responses are JSON objects with id and message if 200 OK is sent.
So something like this would do:

class MailGunResponse {
    public String id;
    public String message;
}

I don't think you have to annotate it with @JsonEntity or something similar, but that's the way to go.

Im using retrofit 2.0 version and got com.sun.jdi.InternalException: Unexpected JDWP Error: 103 error, Any idea ?