[keycloak-user] Send additional parameter on keycloak login

Hello All, After having received so many good reviews about Keycloak, We are implementing Keycloak as the access management system to our client organization. Thanks to all the contributors. I am stuck in getting the login complete with the User Federation SPI. I am in need of sending an additional parameter from the client during login which I wanted to be available in the User Federation layer. So that based on that parameter, I shall make an appropriate request to our legacy system for validating the password. Currently, I do this, curl -X POST \ http://localhost:8080/auth/realms/<realm-name>/protocol/openid-conn... \ -H 'Accept: application/json' \ -H 'Cache-Control: no-cache' \ -H 'Content-Type: application/x-www-form-urlencoded' \ -d 'username=<username>&password=<password>&grant_type=password&client_id=<client-id>' How can I add one another custom param to the body and make it available in the federation layer before making the login request to the legacy system? Any help will be much appreciated. Thanks, Vignesh