code: protected function fillDocument(Document $document, object $object) : bool {
  		if($object instanceof SearchableEntity) {
  			return $object->indexEntity($document);
  		}
  		$mapping = $this->getMapping(\get_class($object));
  		$accessor = PropertyAccess::createPropertyAccessor();
  		foreach($mapping as $fieldName => $propertyPath) {
  			$document->addField($fieldName, $accessor->getValue($object, $propertyPath));
  		}
  		return true;
  	}
docs: Fills the given document based on the object
  
  @param Document $document
  @param object $object
  @return boolean