code: private function createOrGetDefinition(IMetaModelDataDefinition $container)
      {
          if ($container->hasMetaModelDefinition()) {
              return $container->getMetaModelDefinition();
          }
  
          $container->setMetaModelDefinition($definition = new MetaModelDefinition());
  
          return $definition;
      }
docs: Create or get the MetaModel definition.
  
  @param IMetaModelDataDefinition $container The container being built.
  
  @return IMetaModelDefinition