User Story: As a user of Open Liberty, Concurrency, and Java 19 I want to be able to use the new functionality that has been added to Futures and ExecutorServices when using the managed counterpart ...

After merging #2884 the ExecutorService is properly shuts down. However, this issue still appears in SonarCloud. The problem is, that in Java 8 (that we use) ExecutorService has no close method.