EDIT

After upgrading to Unitils 3.x it was needed to add "[NULL]" values to the attributed in the xml datasets since the MultiSchemaXmlDataSetReader use in this version was requiring these values for some reason, otherwise the columns in data tables would have been incomplete. Only the fields for which attributes existe din the first xml element where taken in to account.

Now this issue seems to be fixed in Unitils and cluttering the datasets with "NULL" attributes is no longer needed.