src/Serializer.php
protected function serializeHasOne(Model $owner, Model $model = null, AdapterInterface $adapter)
    {
        return $this->serialize($model, $adapter);
    }
protected function serializeHasOne(Model $owner, Model $model = null, AdapterInterface $adapter)
    {
        return $this->serialize($model, $adapter);
    }
protected function serializeHasOne ( Model $ owner , Model $ model = null , AdapterInterface $ adapter ) { return $ this -> serialize ( $ model , $ adapter ) ; }
Serializes a has-one relationship value

@param   Model                   $owner
@param   Model|null              $model
@param   AdapterInterface        $adapter
@return  array
Serializes a has - one relationship value