Big stack trace when shutting down XWiki if Solr queue is bigger than 0

Steps to reproduce:

1. Start a new XWiki instance
2. Login as an Admin
3. Go to Administration -> Search and make sure the queue is bigger than 0 and descending (it should be around 2800 when first starting the server)
4. Stop XWiki

You'll see a stack trace before the server completely shuts down. I've attached the one I got.