[management] invalid logout url construction with external OIDC Provider

[apoddany]

When using external OIDC Provider, the logout URL is incorrectly built (missing ? character)

OIDC Provider used is CAS from Apereo with the following configuration :

{
    "id": "cas",
    "name": "My IDP",
    "description": "IDP CAS 6.3.x",
    "type": "oidc",
    "enabled": true,
    "configuration": {
        "tokenEndpoint": "https://<idp_host>/oidc/token",
        "clientId": "mysolution",
        "color": "#f39c12",
        "tokenIntrospectionEndpoint": "https://<idp_host>/oidc/introspect",
        "userLogoutEndpoint": "https://<idp_host>/oidc/logout",
        "authorizeEndpoint": "https://<idp_host>/oidc/authorize",
        "clientSecret": "xxx",
        "scopes": [
            "openid",
            "email",
            "profile"
        ],
        "userInfoEndpoint": "https://<idp_host>/oidc/profile"
    },
    "roleMappings": [
...

For the Console, the generated URL will look like :

https://<idp_host>/oidc/logoutahttps%3A%2F%2F<gravitee_host>

It is missing the "?" character.

Currently one workaround is to add the following "?a=a" for the userLogoutEndpoint as :

"userLogoutEndpoint": "https://<idp_host>/oidc/logout?a=a",

This will make the logout Url look like :

https://<idp_host>/oidc/logout?a=ahttps%3A%2F%2F<gravitee_host>

This url is wrong but will allow to disconnect the user.

Adding ?post_logout_redirect_uri=does not improve behavior.

Your Environment

• Version used: 3.5.10
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