code: public function initPicker(PickerInterface $picker)
  	{
  		$attributes = parent::initPicker($picker);
  
  		if (null === $attributes)
  		{
  			return null;
  		}
  
  		$this->blnFiles = isset($attributes['files']) && $attributes['files'];
  		$this->blnFilesOnly = isset($attributes['filesOnly']) && $attributes['filesOnly'];
  
  		if (isset($attributes['path']))
  		{
  			$strPath = (string) $attributes['path'];
  
  			if (Validator::isInsecurePath($strPath) || !is_dir($this->strRootDir . '/' . $strPath))
  			{
  				throw new \RuntimeException('Invalid path ' . $strPath);
  			}
  
  			// Allow only those roots that are allowed in root nodes
  			if (!empty($this->arrFilemounts))
  			{
  				$blnValid = false;
  
  				foreach ($this->arrFilemounts as $strFolder)
  				{
  					if (0 === strpos($strPath, $strFolder))
  					{
  						$blnValid = true;
  						break;
  					}
  				}
  
  				if (!$blnValid)
  				{
  					$strPath = '';
  				}
  			}
  
  			$this->arrFilemounts = array($strPath);
  		}
  
  		if (isset($attributes['extensions']))
  		{
  			$this->arrValidFileTypes = StringUtil::trimsplit(',', strtolower($attributes['extensions']));
  		}
  
  		return $attributes;
  	}
docs: {@inheritdoc}