protected function encodeHeader($header)
{
return preg_replace_callback('/(?:[^A-Za-z0-9_\\-\\.~!\\$@#?&\'\\(\\)\\[\\]\\*\\+,:;=\\/% ]+|%(?![A-Fa-f0-9]{2}))/', function (array $matches) {
return rawurlencode($matches[0]);
}, $header);
}