httpEtagProvider.defineCacheServiceAdapter = function httpEtagDefineCacheServiceAdapter (serviceName, config) {
    if (!config) throw new Error('Missing cache service adapter configuration')
    if (!config.methods) throw new Error('Missing cache service adapter configuration methods')
    external_angular_default.a.forEach(requiredAdapterMethods, function (method) {
      if (typeof config.methods[method] !== 'function') {