Relay State in IDP initiated SSO from external IDP

Hi,
I am implementing IDP(external IDP) initiated SSO with Keycloak as SP provider. Currently I am able to successfully configure the IDP initiated SSO from external IDP, but I see issue with RelayState url
Here is the flow

  • User logs into IDP
  • Click on app which is set for IDP initiated SSO
  • IDP sends SAML assertion along with post param RelayState
    (eg: RelayState → https://server.com/test?userId=123&service=hsia)
  • Keycloak verifies the assertion and logs the user and redirects to https://server.com/test

Seems like Keycloak is not using RelayState sent from external IDP. Anyone faced this issue before?