I just noticed a change in behaviour regarding the exposure of metadata in OAI-PMH interface regarding empty fields.
In 2.4.* versions, when a field is empty, the tag on OAI-PMH is not presented, now, on OJS 3.0.2, there are empty fields presented, example:
This issue is a problem for some harvesters that take the first instance of the tag, in this case, the title.
Is this a new behaviour or just a bug to be fixed?