message: Disable input when IS (NOT) NULL selected in filters
diff: @@ -283,6 +283,7 @@ export default class AdhocFilterEditPopoverSimpleTabContent extends React.Compon
  value={adhocFilter.comparator || ''}
  className="form-control input-sm"
  placeholder={t('Filter value')}
  + disabled={adhocFilter.operator === 'IS NOT NULL' || adhocFilter.operator === 'IS NULL'}
  />
  }
  </FormGroup>
  