[bwilkins30]

That's fine too, and it's sufficient assuming:

1. you have no other consumers of this data that need null values rather than empty string

2. empty fields will always end up with "" (as opposed to null). If null is also possible (eg your JSON service will completely omit certain fields) you could just adjust the criteria to also include NOT_NULL.

Doing this works, thanks :

AdvancedCriteria criteria = new AdvancedCriteria("field5", OperatorId.NOT_NULL);
         
theComboBox.setOptionCriteria(criteria);
theComboBox.setFilterLocally(true);