Undefined index error, when child document class has no annotation

[mindaugasrukas]

When child class has no annotations then getting an undefined error:

Undefined index: ONGR\ContentBundle\Tests\app\fixture\Acme\TestBundle\Document\Product

Trace:
/var/www/ContentBundle/vendor/ongr/elasticsearch-bundle/Mapping/MetadataCollector.php:270
/var/www/ContentBundle/vendor/ongr/elasticsearch-bundle/Mapping/MetadataCollector.php:235
/var/www/ContentBundle/vendor/ongr/elasticsearch-bundle/Mapping/MetadataCollector.php:178
/var/www/ContentBundle/vendor/ongr/elasticsearch-bundle/Mapping/MetadataCollector.php:110
/var/www/ContentBundle/vendor/ongr/elasticsearch-bundle/DependencyInjection/Compiler/MappingPass.php:150
/var/www/ContentBundle/vendor/ongr/elasticsearch-bundle/DependencyInjection/Compiler/MappingPass.php:39
/var/www/ContentBundle/vendor/symfony/symfony/src/Symfony/Component/DependencyInjection/Compiler/Compiler.php:117
/var/www/ContentBundle/vendor/symfony/symfony/src/Symfony/Component/DependencyInjection/ContainerBuilder.php:614
/var/www/ContentBundle/vendor/symfony/symfony/src/Symfony/Component/HttpKernel/Kernel.php:533
/var/www/ContentBundle/vendor/symfony/symfony/src/Symfony/Component/HttpKernel/Kernel.php:127
/var/www/ContentBundle/vendor/symfony/symfony/src/Symfony/Bundle/FrameworkBundle/Test/KernelTestCase.php:141
/var/www/ContentBundle/vendor/symfony/symfony/src/Symfony/Bundle/FrameworkBundle/Test/WebTestCase.php:33
/var/www/ContentBundle/Tests/Functional/DependecyInjection/ONGRContentExtensionTest.php:41