Hello, 
We are experiencing an unusual issue. It might be due to a misconfiguration 
or a bug.

When performing SAML Single Logout (SLO) using HTTP-POST binding, the 
response contains both the SAML logout auto-submit form and also the CAS 
logout page, which cause issues with auto-submit behavior.

Environment:
SimpleSAMLphp as an Identity Provider (IdP), CAS 7.1 as a Service Provider 
(SP)

Current behaviour:
1. CAS correctly generates SAML LogoutRequest  (through pac4j-saml library)
2. Creates an HTML form with auto-submit functionality (through pac4j-saml 
library)
3. Sets correct RelayState for return  (through pac4j-saml library)
4. However, the response also includes the CAS logout page, resulting in a 
combined response  (standard spring webflow)

Additional Observations: 
- This issue doesn't occur with HTTP-Redirect binding (likely because 302 
status prevents rendering). 
cas.authn.pac4j.saml[0].logout-request-binding=urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST
  
# error occurs
#cas.authn.pac4j.saml[0].logout-request-binding=urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect
  
# is OK
- The SAML form is generated during SAML actions in terminateSession state 
- The CAS logout page is added later in the logout flow

Flow Analysis: 
1. terminateSession state executes: 
- delegatedAuthenticationClientLogoutAction 
- delegatedAuthenticationSaml2ClientFinishLogoutAction 
- delegatedSaml2ClientTerminateSessionAction 
2. Flow continues to logoutView state which adds the CAS logout page

Any assistance would be greatly appreciated. 
Kind regards, 
Milan


Example of CAS response:
```
<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8" />
    </head>
    <body onload="document.forms[0].submit()">
        <noscript>
            <p>
                <strong>Note:</strong> Since your browser does not support 
JavaScript,
                you must press the Continue button once to proceed.
            </p>
        </noscript>
        
        <form 
action="https&#x3a;&#x2f;&#x2f;local.xxx.yyy.cz&#x2f;simplesaml&#x2f;module.php&#x2f;saml&#x2f;idp&#x2f;singleLogout"
 
method="post">
            <div>
<input type="hidden" name="RelayState" 
value="https&#x3a;&#x2f;&#x2f;local.xxx.yyy.cz&#x2f;cas&#x2f;login&#x3f;client_name&#x3d;SimpleSAML"/>
 
               
<input type="hidden" name="SAMLRequest" value="PD...dD4="/>                
                
            </div>
            <noscript>
                <div>
                    <input type="submit" value="Continue"/>
                </div>
            </noscript>
        </form>
    </body>
</html><!DOCTYPE html><html lang="en">

<head>
    <meta charset="UTF-8" /><meta http-equiv="X-UA-Compatible" 
content="IE=edge" /><meta name="viewport" content="width=device-width, 
initial-scale=1, shrink-to-fit=no" /><title>Logout successful - CAS - 
Central Authentication Service</title>
    <meta http-equiv="X-UA-Compatible" content="IE=edge"/><meta 
name="viewport" content="width=device-width, initial-scale=1, 
shrink-to-fit=no"/>
        <link rel="stylesheet" type="text/css" 
href="/cas/webjars/normalize.css/8.0.1/normalize-112272e51c80ffe5bd01becd2ce7d656.css"
 
/><link rel="stylesheet" type="text/css" 
href="/cas/webjars/bootstrap/5.3.3/css/bootstrap-grid.min-ea688188986141f98fe7c673dd4c34f1.css"
 
/><link rel="stylesheet" type="text/css" 
href="/cas/webjars/material-components-web/14.0.0/dist/material-components-web.min-9da9033e8d04504fe54b3dbb1298fd78.css"
 
/><link rel="stylesheet" type="text/css" 
href="/cas/webjars/mdi__font/7.4.47/css/materialdesignicons.min-2c83c4bce691e18f82409f87b2bf84e4.css"
 
/><link rel="stylesheet" type="text/css" 
href="/cas/webjars/datatables/2.1.0/css/dataTables.dataTables-dd4fd70bec3081bf43eaf1b44606825c.css"
 
/><link rel="stylesheet" type="text/css" 
href="/cas/css/cas-c344b14a22795665456bd29c9c4007f6.css" /><link 
rel="stylesheet" type="text/css" 
href="/cas/themes/standard/css/cas-custom-91a1a43e65f3bd9385bb00840907affe.css" 
/><link rel="shortcut icon" 
href="/cas/favicon-ee8c1233d027f8132e38212a2bda6bb4.ico" /></head>
....
```

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