/**
  * Create a new ParameterizedHeader with $name, $value and $params.
  * @param string $name
  * @param string $value
  * @param array $params
  * @return Swift_Mime_ParameterizedHeader
  */
 public function createParameterizedHeader($name, $value = null, $params = array())
 {
     $header = new Swift_Mime_Headers_ParameterizedHeader($name, $this->_encoder, strtolower($name) == 'content-disposition' ? $this->_paramEncoder : null);
     if (isset($value)) {
         $header->setFieldBodyModel($value);
     }
     foreach ($params as $k => $v) {
         $header->setParameter($k, $v);
     }
     $this->_setHeaderCharset($header);
     return $header;
 }