ApiService.java

package com.jxw.graphql.service;
//in: app/src/main/java/packageDir/service/

import com.apollographql.apollo.ApolloClient;
import com.jxw.graphql.app.DemoApplication;
import com.jxw.graphql.type.CustomType;
import com.jxw.graphql.utils.CustomDateAdapter;

import okhttp3.OkHttpClient;
import okhttp3.logging.HttpLoggingInterceptor;

public class ApiService {
    /**
     * private constructor.
     * Utility class
     */
    private ApiService() {
    }
    
    /**
     * Returns the Apollo Client instance.
     * @return ApolloClient
     */
    public static ApolloClient getApolloClient(DemoApplication application) {

        HttpLoggingInterceptor loggingInterceptor = new HttpLoggingInterceptor();
        loggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BODY);

        OkHttpClient okHttpClient = new OkHttpClient.Builder()
                .addInterceptor(loggingInterceptor)
                .build();

        return ApolloClient.builder()
                .serverUrl(application.getBaseUrl())
                .okHttpClient(okHttpClient)
                .addCustomTypeAdapter(CustomType.DATETIME, new CustomDateAdapter())
                .build();
    }
}