public AssertedIdentity getIdentity(String identifier) {

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

        return null;

    }
Returns the identity finally asserted by the SAML IdP 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 by the SAML IdP 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 finally asserted by the SAML IdP 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-saml/src/main/java/org/apache/guacamole/auth/saml/acs/SAMLAuthenticationSessionManager.java