add lazy initialization of collection elements
add lazy initialization of collection elements

sphereio/commercetools-php-sdk,sphereio/sphere-php-sdk,sphereio/sphere-php-sdk,sphereio/commercetools-php-sdk,sphereio/sphere-php-sdk,sphereio/sphere-php-sdk,sphereio/commercetools-php-sdk,sphereio/commercetools-php-sdk