src/Request.php
public function toHeader()
    {
        $first = true;
        $out = 'Authorization: OAuth';
        foreach ($this->parameters as $k => $v) {
            if (substr($k, 0, 5) != "oauth") {
                continue;
            }
            if (is_array($v)) {
                throw new TwitterOAuthException('Arrays not supported in headers');
            }
            $out .= ($first) ? ' ' : ', ';
            $out .= Util::urlencodeRfc3986($k) . '="' . Util::urlencodeRfc3986($v) . '"';
            $first = false;
        }
        return $out;
    }
public function toHeader()
    {
        $first = true;
        $out = 'Authorization: OAuth';
        foreach ($this->parameters as $k => $v) {
            if (substr($k, 0, 5) != "oauth") {
                continue;
            }
            if (is_array($v)) {
                throw new TwitterOAuthException('Arrays not supported in headers');
            }
            $out .= ($first) ? ' ' : ', ';
            $out .= Util::urlencodeRfc3986($k) . '="' . Util::urlencodeRfc3986($v) . '"';
            $first = false;
        }
        return $out;
    }
Builds the Authorization: header

@return string
@throws TwitterOAuthException