findAPIKeyPrefix = function (settings) {
  // Need JWT plugin to work with Hapi v17+ to test this again
  /* $lab:coverage:off$ */
  let out = '';
  if (settings.securityDefinitions) {
    Object.keys(settings.securityDefinitions).forEach((key) => {
      if (settings.securityDefinitions[key]['x-keyPrefix']) {
        out = settings.securityDefinitions[key]['x-keyPrefix'];
      }
    });
  }

  return out;
  /* $lab:coverage:on$ */
}
finds any keyPrefix in securityDefinitions - also add x- to name

@param  {Object} settings
@return {string}