How to use the @storefront-api/lib/elastic.adjustBackendProxyUrl function in @storefront-api/lib

if (urlSegments.length < 2) { throw new Error('No index name given in the URL. Please do use following URL format: /api/catalog//_search') } else {
    indexName = urlSegments[1];

    if (urlSegments.length > 2) { entityType = urlSegments[2] }

    if (config.elasticsearch.indices.indexOf(indexName) < 0) {
      throw new Error('Invalid / inaccessible index name given in the URL. Please do use following URL format: /api/catalog//_search')
    }

    if (urlSegments[urlSegments.length - 1].indexOf('_search') !== 0) {
      throw new Error('Please do use following URL format: /api/catalog//_search')
    }
  }

  // pass the request to elasticsearch
  const elasticBackendUrl = adjustBackendProxyUrl(req, indexName, entityType, config)
  const userToken = requestBody.groupToken

  // Decode token and get group id
  if (userToken && userToken.length > 10) {
    const decodeToken = jwt.decode(userToken, config.authHashSecret ? config.authHashSecret : config.objHashSecret)
    groupId = decodeToken.group_id || groupId
  } else if (requestBody.groupId) {
    groupId = requestBody.groupId || groupId
  }

  delete requestBody.groupToken
  delete requestBody.groupId

  let auth = null;

  // Only pass auth if configured