public String getIdentity(String identifier) {

        SSLAuthenticationSession session = resume(identifier);
        if (session != null)
            return session.getIdentity();

        return null;

    }
Returns the identity asserted by the external SSL termination service at
the end of the authentication process represented by the authentication
session with the given identifier. If there is no such authentication
session, or no valid identity has been asserted for that session, null
is returned.

@param identifier
    The unique string returned by the call to defer(). For convenience,
    this value may safely be null.

@return
    The identity asserted by the external SSL termination service at the
    end of the authentication process represented by the authentication
    session with the given identifier, or null if there is no such
    identity.
extensions/guacamole-auth-sso/modules/guacamole-auth-sso-ssl/src/main/java/org/apache/guacamole/auth/ssl/SSLAuthenticationSessionManager.java