Spring WebClient with Apache HTTP client 5 causing memory leak

Question

We've recently upgraded our Spring Boot application and have switched to Spring's new WebClient. On undeploy of the webapp, we see a 'idle-connection-evictor' thread as a memory leak, preventing the WebappClassloader to be gc'ed. That thread is created by the Apache HttpClient 5 (async)

The code creates WebClient instances through a custom WebClientBuilder, with the key code:

public WebClient build() {
    final ServletOAuth2AuthorizedClientExchangeFilterFunction oauth2Client = new ServletOAuth2AuthorizedClientExchangeFilterFunction(
        buildOAuth2AuthorizedClientManager());
    
    CloseableHttpAsyncClient httpAsyncClient = HttpAsyncClients.custom()
        .setConnectionManager(connManager)
        .evictIdleConnections(TimeValue.ofSeconds(60))
        .build();
        
    return WebClient.builder()
        .clientConnector(new HttpComponentsClientHttpConnector(httpAsyncClient))
        .apply(oauth2Client.oauth2Configuration())
        .build();
}

That CloseableHttpAsyncClient already reeks, as there's no try-with-resource. HttpComponentsClientHttpConnector is Closeable, but clientConnector() then just wants a ClientHttpConnector, which has no methods defined for close/destroy/etc. Spring WebClient itself is also neither Closeable nor offers any shutdown/destroy method.

What is the clean way to make a Spring WebClient close its clientConnector?