<?php

namespace MainBundle\Controller\AndroidApi\v1;

use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Symfony\Component\HttpFoundation\Response;
use JMS\Serializer\SerializationContext;
use FOS\RestBundle\Controller\Annotations as FosRest;

/**
 * @FosRest\NamePrefix("api_android_countries_")
 */
class CountryController extends Controller
{
    public function getAction()
    {
        $countries = $this
            ->get('main.country.service')
            ->getCountries();

        $serializer = $this->get('serializer');

        return new Response(
            $serializer->serialize(
                $countries,
                'json',
                SerializationContext::create()->setGroups(array('list'))
            )
        );
    }
}

<?php

namespace MainBundle\Controller\AndroidApi\v1;

use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Symfony\Component\HttpFoundation\Response;
use JMS\Serializer\SerializationContext;
use FOS\RestBundle\Controller\Annotations as FosRest;

/**
 * @FosRest\NamePrefix("api_android_countries_")
 */
class CountryController extends Controller
{
    public function getAction()
    {
        $countries = $this
            ->get('main.country.service')
            ->getCountries();

        $serializer = $this->get('serializer');

        return new Response(
            $serializer->serialize(
                $countries,
                'json',
                SerializationContext::create()->setGroups(array('details'))
            )
        );
    }
}

Add details on Android getCountry API.
Add details on Android getCountry API.
