Retrofit bug, exception on http201 with empty body

RetrofitBug.java

package nl.frankkie.retrofitbug;

import org.junit.Rule;
import org.junit.Test;

import okhttp3.ResponseBody;
import okhttp3.mockwebserver.MockResponse;
import okhttp3.mockwebserver.MockWebServer;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;
import retrofit2.http.GET;
import retrofit2.http.POST;

import static junit.framework.Assert.assertEquals;
import static junit.framework.Assert.assertTrue;
import static junit.framework.Assert.fail;

/**
 * Created by frankb on 22/09/2017.
 */

public class RetrofitBug {
    @Rule
    public final MockWebServer server = new MockWebServer();

    interface MyRestService {
        @GET("/two_zero_four")
        Call<MyEmptyResponseBody> giveMe204NoContent();

        @POST("/two_zero_one")
        Call<MyEmptyResponseBody> giveMe201CreatedWithoutContent();
    }

    public class MyEmptyResponseBody {
        //this class is intentionally empty
    }

    @Test
    public void test() throws Exception {
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl(server.url("/"))
                .addConverterFactory(GsonConverterFactory.create())
                .build();
        MyRestService restService = retrofit.create(MyRestService.class);

        MockResponse mockResponse204 = new MockResponse();
        mockResponse204.setResponseCode(204);
        server.enqueue(mockResponse204);

        MockResponse mockResponse201 = new MockResponse();
        mockResponse201.setResponseCode(201);
        mockResponse201.setHeader("Location", "/two_zero_one/randomId");
        server.enqueue(mockResponse201);

        Call<MyEmptyResponseBody> call204 = restService.giveMe204NoContent();
        try {
            Response<MyEmptyResponseBody> response204 = call204.execute();
            assertEquals(204, response204.code());
            assertTrue(response204.isSuccessful());
        } catch (Throwable t) {
            fail();
        }

        Call<MyEmptyResponseBody> call201 = restService.giveMe201CreatedWithoutContent();
        try {
            Response<MyEmptyResponseBody> response201 = call201.execute();
            assertEquals(201, response201.code());
            assertTrue(response201.isSuccessful());
        } catch (Throwable t) {
            fail();
            //This is the bug.
            //201 can have an empty body, just like 204 does.
            //But at 204, it generates an Exception
        }
    }
}