code: def restore_descriptor(self, converted_descriptor):
          
  
          # Convert
          fields = []
          for field in converted_descriptor['fields']:
              field_type = self.restore_type(field['type'])
              resfield = {
                  'name': field['name'],
                  'type': field_type,
              }
              if field.get('mode', 'NULLABLE') != 'NULLABLE':
                  resfield['constraints'] = {'required': True}
              fields.append(resfield)
          descriptor = {'fields': fields}
  
          return descriptor
docs: Restore descriptor rom BigQuery