buildFilterQuery example

  public function overview(Request $request) {

    $filter = $this->buildFilterQuery($request);
    $rows = [];

    $classes = static::getLogLevelClassMap();

    $this->moduleHandler()->loadInclude('dblog', 'admin.inc');

    $build['dblog_filter_form'] = $this->formBuilder()->getForm('Drupal\dblog\Form\DblogFilterForm');

    $header = [
      // Icon column.       '',
      [