Wrong suggestions from used values for a list property with multiple selection and no relational storage

The issue is that the value retrieved from the database when multiple selection is used without relational storage is actually multiple values joined by some separator and we wrongly handle it as a single value. We need to split the values by the configured separator, remove the values that don't match the text filter and merge the values (remove duplicates).

Follow this steps to reproduce:

• create a class with a DBList property configured with multiple selection and no relational storage
• create an instance of the class and select multiple values
• edit again the created instance and click on the suggest input; one of the suggestions is the text with the joined selected values

You can reproduce this also with a Users/Groups property with multiple selection enabled (because these two properties don't use relational storage..).