Docs: WebClient OAuth2 Setup for Reactive Applications might be wrong

In the reference doc there is an example for a WebClient with OAuth2 Setup for Reactive Applications: https://docs.spring.io/spring-security/site/docs/current/reference/html5/#webclient-setup

    @Bean
    WebClient webClient(ReactiveClientRegistrationRepository clientRegistrations, ServerOAuth2AuthorizedClientRepository authorizedClients) {
        ServerOAuth2AuthorizedClientExchangeFilterFunction oauth =
                new ServerOAuth2AuthorizedClientExchangeFilterFunction(clientRegistrations, authorizedClients);
        oauth.setDefaultClientRegistrationId("keycloak");
        return WebClient.builder()
                .filter(oauth)
                .build();
    }

But in my szenario it leads to an exception:

java.lang.IllegalArgumentException: serverWebExchange cannot be null
	at org.springframework.security.oauth2.client.web.DefaultReactiveOAuth2AuthorizedClientManager.lambda$authorize$4(DefaultReactiveOAuth2AuthorizedClientManager.java:131) ~[spring-security-oauth2-client-5.3.1.RELEASE.jar:5.3.1.RELEASE]
	Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
	|_ checkpoint ⇢ Request to GET https://abc.de/service/api/endpoint?x=0&y=0&z=0 [DefaultWebClient]
Stack trace:
		at org.springframework.security.oauth2.client.web.DefaultReactiveOAuth2AuthorizedClientManager.lambda$authorize$4(DefaultReactiveOAuth2AuthorizedClientManager.java:131) ~[spring-security-oauth2-client-5.3.1.RELEASE.jar:5.3.1.RELEASE]
		at reactor.core.publisher.MonoErrorSupplied.subscribe(MonoErrorSupplied.java:70) ~[reactor-core-3.3.4.RELEASE.jar:3.3.4.RELEASE]
		at reactor.core.publisher.Mono.subscribe(Mono.java:4210) ~[reactor-core-
...

However, switching the ServerOAuth2AuthorizedClientRepository to a ReactiveOAuth2AuthorizedClientService makes the code run.

    @Bean
    WebClient webClient(ReactiveClientRegistrationRepository clientRegistrations, ReactiveOAuth2AuthorizedClientService authorizedClientService) {
        ServerOAuth2AuthorizedClientExchangeFilterFunction oauth = new ServerOAuth2AuthorizedClientExchangeFilterFunction(new AuthorizedClientServiceReactiveOAuth2AuthorizedClientManager(clientRegistrations, authorizedClientService));
        oauth.setDefaultClientRegistrationId("keycloak");
        return WebClient.builder()
                .filter(oauth)
                .build();
    }

spring-security-config:5.3.1.RELEASE
spring-security-oauth2-client:5.3.1.RELEASE
spring-boot-starter-parent:2.2.6.RELEASE
spring-boot-starter-webflux:2.2.6.RELEASE

Is that an issue or am I handling something wrong? I am not sure if there is a correlation but, the working code example does not retrieve a new token, when Mono.retryWhen(...) is used.