Retrofit2 Service Generator

ServiceGenerator.java

public class ServiceGenerator {

    private static final String API_BASE_URL = "https://api.github.com/";

    private static Retrofit retrofit;

    private static Gson mGson = new GsonBuilder()
            .setDateFormat("yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'SSS'Z'")
            .create();

    private static Retrofit.Builder builder = new Retrofit.Builder()
            .baseUrl(API_BASE_URL)
            .addConverterFactory(GsonConverterFactory.create(mGson));

    private static OkHttpClient.Builder httpClient = new OkHttpClient.Builder();

    private static HttpLoggingInterceptor logging = new HttpLoggingInterceptor()
            .setLevel(HttpLoggingInterceptor.Level.BODY);

    public static <S> S createService(Class<S> serviceClass) {
       
       if (!httpClient.interceptors().contains(logging)) {
           httpClient.addInterceptor(logging);
           builder.client(httpClient.build());
           retrofit = builder.build();
       }

        retrofit = builder.client(httpClient.build()).build();

        return retrofit.create(serviceClass);
    }
  
    /**
     * or Error Handing when non-OK response is received from Server
     */
    @NonNull
    public static Retrofit retrofit() { 
        OkHttpClient client =  httpClient.build();;
        return builder.client(client).build();
    }