[question] How to add xml declaration to marshalDocument

Hi,

I just started with jsonix in my project. I succesfully created a mapping from an xsd and I am able to create a marshalDocument.
But whether I use marshalString or marshalDocument, there is no xml declaration (eg. ``) present in the generated xml.

I've searched github and stackoverflow, but I'm unable to find an answer on how to add a xml declaration using jsonix.