AutoFill username for Office 365 Federation

Hi. I found that I had to add an additional iRule on the http_request to parse the referer to get the username and then append it to the URI if it contained a username parameter. Here is my final iRule

when HTTP_REQUEST {
     if { [HTTP::uri] starts_with "/saml/idp/profile/redirectorpost/sso" } {
          if { [HTTP::header exists "Referer"] } {
               set received_referer [HTTP::header "Referer"]
               log local0. $received_referer
               if { $received_referer contains "username="} {
                    log local0. "referer has username"
                    set username [URI::decode [URI::query $received_referer username]]
                    log local0. $username
                     HTTP::uri "/saml/idp/profile/redirectorpost/sso?username=[string map -nocase {"@" "%40"}$username]"
               }
               unset received_referer
           }
     }
}
when ACCESS_POLICY_AGENT_EVENT { 
if { [ACCESS::policy agent_id] eq "GetURIusername" } {
    set username [string map -nocase {"%40" "@"} [URI::query [ACCESS::session data get session.server.landinguri] username]]
    log local0. "NewUsername = $username"
    if  {$username != ""} {
         ACCESS::session data set session.custom.foundusername "1"  
         ACCESS::session data set session.custom.upn $username
         ACCESS::session data set session.logon.last.username $username
    }
}
}