There is static field based singletons at template files. Those singletons making hard to write tests. In my view, We should get rid of those static fields. Generally it's bad design choice.

I have found some of those:
https://github.com/vlingo/vlingo-xoom/blob/master/src/main/resources/codegen/java/JournalProvider.ftl#L26
https://github.com/vlingo/vlingo-xoom/blob/master/src/main/resources/codegen/java/ProjectionDispatcherProvider.ftl#L22
https://github.com/vlingo/vlingo-xoom/blob/master/src/main/resources/codegen/java/StateStoreProvider.ftl#L34

Event this. I don't see any particular reason to declare static field here.
https://github.com/vlingo/vlingo-xoom/blob/master/src/main/resources/codegen/java/DefaultBootstrap.ftl#L20