'(empty)' filter doesn’t work with DB list properties that accept multiple values

Issue original was reproduced on XWiki 16.10.8. But I also have same result in latest one (on ticket creation date 17.10.-RC).

Credit's to slauriere who helped to identify the issue.

Steps to reproduce

1. Modify page

   Help.Applications.Movies.Code.MoviesClass

   in class editor

2. Find DBList property and checkbox mutliselect and relational storage values
3. Save changes
4. Create a new entry for Movie AWM but don't put director value
5. Create LD either on page

   Help.Applications.Movies.WebHome

6. Use this source

   {{liveData
     id="movies"
     properties="doc.name,doc.title, databaseList1"
     source="liveTable"
     sourceParameters="className=Help.Applications.Movies.Code.MoviesClass&translationPrefix=movies.livetable."
   /}}
   

7. Try to filter LD by empty value in director column

Actual result

LD returns emptiness with text (No entries).

Expected result

LD return entry(ies) that doesn't have director value