public function build($config)
{
$config->addField('id', new NonNullType(new IdType()))->addField('name', new NonNullType(new StringType()))->addField('friends', ['type' => new ListType(new CharacterInterface()), 'resolve' => function ($droid) {
return StarWarsData::getFriends($droid);
}])->addField('appearsIn', new ListType(new EpisodeEnum()))->addField('homePlanet', TypeMap::TYPE_STRING);
}