public function addProcessor(AbstractProcessor $processor)
    {
        if (empty($this->_processors)) {
            $this->_processors['processors'] = $processor->toArray();
            $this->_params['processors'] = [];
        } else {
            $this->_processors['processors'] = \array_merge($this->_processors['processors'], $processor->toArray());
        }

        return $this;
    }