[keycloak-user] Realm resolver

We're using KeycloakConfigResolver to resolve the realm based on the request URI. But if we are unable to resolve to a specific realm we want forward the user to a page where she can enter the email address from which we can figure out the user's realm. Since KeycloakConfigResolver cannot be used to redirect the request, any suggestions are how to forward to the page to manual resolution? We are using the Keycloak wildfly adapter. Thanks,