Doctrine\ODM\MongoDB\PersistentCollection::offsetSet PHP Method

    public function offsetSet($offset, $value)
    {
        if ( ! isset($offset)) {
            return $this->add($value);
        }
        return $this->set($offset, $value);
    }

 /**
  * {@inheritdoc}
  */
 public function offsetSet($offset, $value)
 {
     return $this->collection->offsetSet($offset, $value);
 }