Allow new entries on nuxeo-selectivity using data property

Take (for example) the usage of nuxeo-selectivity in nuxeo-add-to-collection-button:
When using nuxeo-selectivity with the operation property, inserting a string that doesn't match any of the suggestions (exactly), there's the possibility to create a new entry. However, if the values are provided through the data property (and not through the operation property) the same behaviour doesn't apply.
The goal would be to have the same behaviour in both cases, regardless of how the element gets the suggestion values.