yii\httpclient\Message::setData PHP Method

    public function setData($data)
    {
        $this->_data = $data;
        return $this;
    }

 /**
  * @inheritdoc
  */
 public function setData($data)
 {
     if ($this->isPrepared) {
         $this->setContent(null);
         $this->isPrepared = false;
     }
     return parent::setData($data);
 }