I would like to access the underlying lists (before and after) based on detection of a ListChange when diffing two entities. All I have direct access to is the list elements that have changed through ContainerElementChange.
Other PropertyChange types accommodate this, but unfortunately ListChange does not appear to.
Is this possible?
No, there is no access to underlying lists from ListChange items. We had some discussion about this in last year (see https://github.com/javers/javers/issues/202) concerning ArrayChange. You can put a feature request to our issues.