OidcIdTokenDecoderFactory caches JwtDecoders and ignores ClientRegistration updates

[iigolovko]

Hello.
OidcIdTokenDecoderFactory caches JwtDecoders and ignores ClientRegistration updates.
It's required to provide uncached way to build JwtDecoder based on actual ClientRegistration.

For example we have a custom ClientRegistrationRepository that uses db to store ClientRegistrations.
It is expected that the settings can be changed dynamically. But OidcIdTokenDecoderFactory caches first created JwtDecoder by registrationId. And if we need to change value of jwsAlgorithm either jwksUri, we can't do it without the restarting of our application.

For now it can be asf crutch

OidcIdTokenDecoderFactory must provide a way to prevent caching of JwtDecoders.

For now, this can only be achieved with a dirty crutch below (via creation of new OidcIdTokenDecoderFactory everytime we need to access JwtDecoder).

@RequiredArgsConstructor
public class SsoOidcIdTokenDecoderFactory implements JwtDecoderFactory<ClientRegistration> {
    private final Function<ClientRegistration, JwsAlgorithm> jwsAlgorithmResolver;

    @Override
    public JwtDecoder createDecoder(ClientRegistration clientRegistration) {
        OidcIdTokenDecoderFactory tempFactory = new OidcIdTokenDecoderFactory();
        tempFactory.setJwsAlgorithmResolver(this.jwsAlgorithmResolver);
        return tempFactory.createDecoder(clientRegistration);
    }
}

I prepared PR that fixes it. #16647
If you have a better idea, you are welcome.