protected function buildFieldFilterSpec(EmbeddedEntityListAttribute $embed_attribute)
 {
     $filter_parts = [];
     $parent_attribute = $embed_attribute->getParent();
     while ($parent_attribute) {
         $filter_parts[] = $parent_attribute->getName();
         $parent_attribute = $parent_attribute->getParent();
     }
     $filter_parts[] = $embed_attribute->getName();
     $filter_parts[] = 'referenced_identifier';
     return implode('.', $filter_parts);
 }