The engineListeners, where and how are they used?

[edugrip]

Was trying to understand the code ( I am not much experienced in concurrency). in Bootstrap.java how are the engineListeners being used? we are creating a placeholder for them, but we are not assigning anything to those variables, example private final ModifiedObjectWriter modifiedObjectWriter; private final EngineSnapshotTaker engineSnapshotTaker; private final OrderBookSnapshotTaker orderBookSnapshotTaker; private final List engineListeners; Top three classes are clearly not being used, engineListener is being use but it appears to be an empty List. Please guide.

[greensheng]

These objects are injected through spring ioc see：https://www.studytonight.com/spring-framework/spring-configuration-using-java-no-xml