We have the following scenario:

1. Multiple 'legacy' Spring Security Oauth2 Auth Servers (2.3.4) - each with a different RSA key configured for creation of the JWT tokens.
2. Single newer (SS 5.3.3, SB 2.3.1) Resource Server which we want to accept tokens from **either** auth server.

Problem is the resource server is only configured with 1 key (currently)- so it can only accept tokens from 1 auth-server.  

Is there any conceivable way to support multiple keys in our resource server to decode JWTs coming from different auth-servers?

We basically want to do this but with multiple keys:
<https://docs.spring.io/spring-security/site/docs/current/reference/html5/#oauth2resourceserver-jwt-decoder-public-key>

Spring Security 5.3 indicates this may be possible with 'multi-tenancy' <https://docs.spring.io/spring-security/site/docs/current/reference/html5/#webflux-oauth2resourceserver-multitenancy>

It's a basic configuration

```
    @Value("${security.oauth2.resourceserver.jwt.key-value}")
    RSAPublicKey key;

    @Override
    protected void configure(HttpSecurity http) throws Exception {

        http

                // using new Spring Security SpE"{{LOCATOR_BASE_URL}}"L
                //https://docs.spring.io/spring-security/site/docs/current/reference/htmlsingle/#webflux-oauth2resourceserver-jwt-authorization
                .authorizeRequests(authorizeRequests ->
                                authorizeRequests

                                        .antMatchers("/shipments/**").hasAuthority("SCOPE_DOMPick")
                                                                               .anyRequest().authenticated()
                )

                .csrf().disable()

                // ****** this is the new DSL way in Spring Security 5.2 instead of Spring Security Oauth @EnableResourceServer ******
                .oauth2ResourceServer(oauth2ResourceServer ->
                        oauth2ResourceServer
                                .jwt(jwt ->
                                        jwt.decoder(jwtDecoder())
                                )
                );

    }

    // static key
    @Bean
    JwtDecoder jwtDecoder() {
        return NimbusJwtDecoder.withPublicKey(this.key).build();

```