DDC-2974: [GH-950] Can cache empty collections

[doctrinebot]

Jira issue originally created by user @doctrinebot:

This issue is created automatically through a Github pull request on behalf of goetas:

Url: #950

Message:

I should be able to cache an "empty" collection.

I have a some objects, where 90% of these have on-to-many relations with zero associated elements.
This causes doctrine to run a query each time, instead of cache it as empty relation.

[doctrinebot]

Comment created by @doctrinebot:

A related Github Pull-Request [GH-950] was closed:
#950

[doctrinebot]

Comment created by @FabioBatSilva:

Fixed by : a3b4104

[doctrinebot]

Issue was closed with resolution "Fixed"