Allow to provide a `ClientHttpRequestInterceptor` for the RestClient used by OAuth2 client

Expected Behavior

Allow to provide a ClientHttpRequestInterceptor for the RestClient used by OAuth2 client.

Current Behavior

Not possible to provide or set a ClientHttpRequestInterceptor.

Context

In the RestClient used by the Spring Security OAuth2 client I would like to provide a custom ClientHttpRequestInterceptor.

I solved it with a custom OAuth2AccessTokenResponseClient bean, but this requires to duplicate the internal AbstractRestClientOAuth2AccessTokenResponseClient to create the RestClient with the neccessary message converters and error repsonse handler.

    @Bean
    OAuth2AccessTokenResponseClient<OAuth2ClientCredentialsGrantRequest> clientCredentialsTokenResponseClient(
            LogbookClientHttpRequestInterceptor logbookInterceptor) {

        // Copied from
        // https://github.com/spring-projects/spring-security/blob/main/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/AbstractRestClientOAuth2AccessTokenResponseClient.java#L65-L71
        var restClient = RestClient.builder()
                .configureMessageConverters(converters -> converters
                        .disableDefaults()
                        .addCustomConverter(new FormHttpMessageConverter())
                        .addCustomConverter(new OAuth2AccessTokenResponseHttpMessageConverter()))
                //                .messageConverters(converters -> {
                //                    converters.clear();
                //                    converters.add(new FormHttpMessageConverter());
                //                    converters.add(new OAuth2AccessTokenResponseHttpMessageConverter());
                //                })
                .defaultStatusHandler(new OAuth2ErrorResponseErrorHandler())
                // Apply the logbook request interceptor.
                .requestInterceptor(logbookInterceptor)
                .build();

        var client = new RestClientClientCredentialsTokenResponseClient();
        client.setRestClient(restClient);

        return client;
    }

Start with oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/AbstractRestClientOAuth2AccessTokenResponseClient.java and review how its RestClient is built. Trace the RestClientClientCredentialsTokenResponseClient usage and existing configuration points; done means callers can provide a ClientHttpRequestInterceptor without duplicating the internal client setup or changing its message converters and error handling.