protected function _vcl_sub_synth_https_fix()
    {
        $tpl = $this->_vcl_sub_synth();

        if ( ! $tpl) {
            $tpl = <<<EOS
sub vcl_synth {
    if (resp.status == 750) {
        set resp.status = 301;
        set resp.http.Location = "https://" + req.http.host + req.url;
        return(deliver);
    }
}
EOS;
        } else{
            $tpl_750 = '
sub vcl_synth {
    if (resp.status == 750) {
        set resp.status = 301;
        set resp.http.Location = "https://" + req.http.host + req.url;
        return(deliver);
    }';

        $tpl = str_ireplace('sub vcl_synth {', $tpl_750, $tpl);
        }

        return $tpl;
    }