degov-8.x-2.0/modules/degov_search_content/degov_search_content.module

<?php

/**
 * Implements hook_facets_search_api_query_type_mapping_alter().
 */
function degov_search_content_facets_search_api_query_type_mapping_alter($backend_plugin_id, array &$query_types) {
  $query_types['date'] = 'search_api_degov_date_range';
}