code: def addDocument(self, row_dict, folder):
      
      if folder:
          # This content type need a file
          if row_dict.get('File', None):
              path = resource_filename(
                  self.dataset_project,
                  "setupdata/%s/%s" % (self.dataset_name,
                                       row_dict['File'])
              )
              try:
                  file_data = read_file(path)
              except Exception as msg:
                  file_data = None
                  logger.warning(msg[0] + " Error on sheet: " + self.sheetname)
  
              # Obtain all created instrument documents content type
              catalog = getToolByName(self.context, 'bika_setup_catalog')
              documents_brains = catalog.searchResults({'portal_type': 'Multifile'})
              # If a the new document has the same DocumentID as a created document, this object won't be created.
              idAlreadyInUse = False
              for item in documents_brains:
                  if item.getObject().getDocumentID() == row_dict.get('DocumentID', ''):
                      warning = "The ID '%s' used for this document is already in use on instrument '%s', consequently " \
                                "the file hasn't been upload." % (row_dict.get('DocumentID', ''), row_dict.get('instrument', ''))
                      self.context.plone_utils.addPortalMessage(warning)
                      idAlreadyInUse = True
              if not idAlreadyInUse:
                  obj = _createObjectByType("Multifile", folder, tmpID())
                  obj.edit(
                      DocumentID=row_dict.get('DocumentID', ''),
                      DocumentVersion=row_dict.get('DocumentVersion', ''),
                      DocumentLocation=row_dict.get('DocumentLocation', ''),
                      DocumentType=row_dict.get('DocumentType', ''),
                      File=file_data
                  )
                  obj.unmarkCreationFlag()
                  renameAfterCreation(obj)
                  notify(ObjectInitializedEvent(obj))
docs: This function adds a multifile object to the instrument folder
      :param row_dict: the dictionary which contains the document information
      :param folder: the instrument object