As seen in https://github.com/spring-projects/spring-boot/issues/26214#issuecomment-856009156, the HttpComponentsClientHttpConnector can be instantiated with a custom client instance or create a default one. The connector implementation doesn't provide access to the underlying client nor implements the Closeableinterface.
We should ensure that the connector can close the resources it's using. This should not be done through the WebClient interface since client resources can be shared amongst clients or even with the server.
In the case of the HttpComponentsClientHttpConnector in Spring Boot, it is created as a Spring bean and will be considered when components are shut down.
Comment From: JanHron
@bclozel I realized I never thanked you for the quick fix of this. It actually solved our problem back then; if we ever meet on a conference or something, I'll treat you to a beer or another tasty beverage of your choice ;-)