my $res = $ua->request(POST $url,
                       'user-agent'                  => 'Mozilla/5.0',
                       ':member_verbosity_threshold' => 0,
                       ':csrf_token'                 => '2802000000...',
#-- not required:      'content-type'                => 'application/x-www-form-urlencoded',
                      );
 
##</code><code>##

POST /xxx HTTP/1.1
TE: deflate,gzip;q=0.3
Connection: TE, close
Host: localhost:5000
User-Agent: Mozilla/5.0
Content-Length: 0
Content-Type: application/x-www-form-urlencoded
csrf_token: 28020000006.....
member_verbosity_threshold: 0
    

##</code><code>##

 my $res2 = $ua->request(POST $url,
                       'user-agent'                  => 'Mozilla/5.0',
                       ':member_verbosity_threshold' => 0,
#-- not in header:     ':csrf_token'                 => '28020000006.....',
                       Content                       => [ csrf_token => '28020000006.....', ]  #-- but in body
                      );

##</code><code>##

POST /xxx HTTP/1.1
TE: deflate,gzip;q=0.3
Connection: TE, close
Host: localhost:5000
User-Agent: Mozilla/5.0
Content-Length: 27
Content-Type: application/x-www-form-urlencoded
member_verbosity_threshold: 0

csrf_token=28020000006.....