retrofit.java

import okhttp3.ConnectionSpec;
import okhttp3.OkHttpClient;
import org.junit.Test;
import retrofit2.Call;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;
import retrofit2.http.GET;
import retrofit2.http.Path;

import java.io.IOException;
import java.util.Collections;
import java.util.Map;

public class RestFactoryTest {

    @Test
    public void teste() throws IOException {

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://api.github.com")
                .addConverterFactory(GsonConverterFactory.create())
                .client(new OkHttpClient.Builder().connectionSpecs(Collections.singletonList(ConnectionSpec.MODERN_TLS)).build())
                .build();

        GitHubService service = retrofit.create(GitHubService.class);
        Response<Map<String, String>> execute = service.getUser("clairtonluz").execute();
        Map<String, String> body = execute.body();
        System.out.println(body);
    }

    private static interface GitHubService {

        @GET("users/{username}")
        Call<Map<String, String>> getUser(@Path("username") String username);
    }
}