/**
  * Adds many_many relationships based off relationship_name and related_class_name, and many_many_extraFields such as 'Sort'.
  *
  * @param null $class
  * @param null $extension
  * @return array
  */
 public function extraStatics($class = null, $extension = null)
 {
     $extra = [];
     if (static::sortable()) {
         $extra = ['many_many_extraFields' => [static::relationship_name() => [static::SortFieldName => 'Int']]];
     }
     return array_merge_recursive(parent::extraStatics($class, $extension), $extra, ['many_many' => [static::relationship_name() => static::related_class_name()]]);
 }
 public function extraStatics($class = null, $extension = null)
 {
     return array_merge_recursive(parent::extraStatics($class, $extension) ?: [], ['has_many' => [static::RelationshipName => static::RelatedClassName]]);
 }