title: Retrofit 2.0-beta-2 is adding literal quotes to MultiPart values
body: <p>Went to upgrade to Retrofit 2.0 and running into this weird problem.</p>
  
  <p>I have a method to log a user in</p>
  
  <pre><code>public interface ApiInterface {
  
      @Multipart
      @POST("user/login/")
      Call&lt;SessionToken&gt; userLogin(@Part("username") String username, @Part("password") String password);
  }
  </code></pre>
  
  <p>When I look at the key value POST params on the server side they print like this</p>
  
  <pre><code>username : "brian"
  password : "password"
  </code></pre>
  
  <p>The same method using retrofit 1.9 the K:V pairs look like</p>
  
  <pre><code>username : brian
  password : password
  </code></pre>
  
  <p>It's adding literal quotes to the POST variables</p>
  
  <p>If I use any other rest client the variables print like the second way without the quotes.</p>
  
  <p>Here is how I build the Retrofit instance with an interceptor</p>
  
  <pre><code> OkHttpClient client = new OkHttpClient();
      client.interceptors().add(new Interceptor() {
          @Override
          public Response intercept(Chain chain) throws IOException {
              Request original = chain.request();
  
              // Customize the request
              Request request = original.newBuilder()
                      .header("Accept", "application/json")
                      .header("Authorization", myPrefs.accessToken().getOr(""))
                      .method(original.method(), original.body())
                      .build();
  
              Response response = chain.proceed(request);
  
              // Customize or return the response
              return response;
          }
      });
  
      Ok2Curl.set(client);
  
      Retrofit retrofit = new Retrofit.Builder()
              .baseUrl(apiEndpoint)
              .addConverterFactory(GsonConverterFactory.create())
              .client(client)
              .build();
  </code></pre>
  
  <p>I imagine i'm doing something wrong with the converter but not sure what.</p>
  
  <p>Has anyone else ran into this problem yet? I know its in beta but it's pretty widly used.</p>