code: def derive_link_fields(self, context):
          
          if self.link_fields is not None:
              return self.link_fields
  
          else:
              link_fields = set()
              if self.fields:
                  for field in self.fields:
                      if field != 'is_active':
                          link_fields.add(field)
                          break
  
          return link_fields
docs: Used to derive which fields should be linked.  This should return a set() containing
          the names of those fields which should be linkable.