code: public function getSiblings($objFilter)
      {
          if (!$this->getMetaModel()->hasVariants()) {
              return null;
          }
          return $this->getMetaModel()->findVariantsWithBase(array($this->get('id')), $objFilter);
      }
docs: Find all Variants including the variant base.
  
  The item itself is excluded from the return list.
  
  @param IFilter $objFilter The additional filter settings to apply.
  
  @return null|IItems