yupe\components\behaviors\FileUploadBehavior::generateFilename PHP Method

    public function generateFilename()
    {
        if (is_callable($this->fileName)) {
            $name = call_user_func($this->fileName);
        } else {
            $name = md5(uniqid($this->getOwner()->{$this->attributeName}, true));
        }
        $name .= '.' . $this->getUploadedFileInstance()->getExtensionName();
        return $name;
    }