upload_maxsize field unavailable in the default XWiki.XWikiPreferences class ?

Hi !

Would it be possible to add a "upload_maxsize" property to the
XWiki.XWikiPreferences class? Instead of having to add it yourself in
the class when you need it.
For example, when you reset the database and want to import your
backup archive, if the archive is too big then you are stuck. Because
when you try to edit the XWiki.XWikiPreferences class to add the
upload_maxsize property, there is no button to add a property to the
class. So basically I think you are stuck.
I think the best solution would be to have the upload_maxsize field
present by default, like all the other fields, in the
XWiki.XWikiPreferences class. However I dont know how to do this on my
installation, and maybe it would be nice to have it in XWiki.

thanks