@Override
    public PublicJsonWebKey getJsonWebKeySigningKey(final Optional<OAuthRegisteredService> registeredService) throws Throwable {
        val jwks = jsonWebKeySet.getJsonWebKeys();
        FunctionUtils.throwIf(jwks.isEmpty(),
            () -> new IllegalArgumentException("Json web keystore is empty and contains no keys"));
        return (PublicJsonWebKey) jwks.getFirst();
    }
This is {@link UmaRequestingPartyTokenSigningService}.

@author Misagh Moayyed
@since 6.0.0
support/cas-server-support-oauth-uma-core/src/main/java/org/apereo/cas/uma/ticket/rpt/UmaRequestingPartyTokenSigningService.java