on Plone 4.2 this is always going to return None as the **displayPublicationDateInByline** property [was introduced on Plone 4.3](https://github.com/plone/plone.app.upgrade/blob/1.3a1/plone/app/upgrade/v43/profiles/to_alpha1/propertiestool.xml).

how are we going to solve it?

I could propose to add the property on an upgrade step, but we have to be careful and modify later plone.app.upgrade and make it not overwrite the value using **purge="False"**.

does this makes sense @ericof @jpgimenez?