Improve user experience for BooleanJunction


 - https://hibernate.atlassian.net/browse/HSEARCH-1616
> It's an interesting point of view.
> My reasoning is that the user is possibly chaining the BooleanQuery to other restrictions 

But maybe not. Match all seems odd to me.

> I'm fine to change the AssertionFailure into a SearchException : probably safer? 

I could live with that. It is a better exception for sure. AssertionFailure is really for "internal" usage imo.