text: /*
   * Copyright 2020 Adobe. All rights reserved.
   * This file is licensed to you under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License. You may obtain a copy
   * of the License at http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under
   * the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
   * OF ANY KIND, either express or implied. See the License for the specific language
   * governing permissions and limitations under the License.
   */
  const VARY_HDR_VERSION_LOCK = 'x-ow-version-lock';
  
  function vary(func) {
    return async (req, context) => {
      const resp = await func(req, context);
      const v = resp.headers.get('vary') || '';
      if (v.toLowerCase().indexOf(VARY_HDR_VERSION_LOCK) < 0) {
        resp.headers.set('vary', v ? `${v},${VARY_HDR_VERSION_LOCK}` : VARY_HDR_VERSION_LOCK);
      }
      return resp;
    };
  }
  
  module.exports = vary;
  