code: public com.google.protobuf.Duration getDefaultExpiration() {
      return defaultExpiration_ == null ? com.google.protobuf.Duration.getDefaultInstance() : defaultExpiration_;
    }
docs: <pre>
  Duration that static files should be cached by web proxies and browsers.
  Only applicable if the corresponding
  [StaticFilesHandler](https://cloud.google.com/appengine/docs/admin-api/reference/rest/v1/apps.services.versions#staticfileshandler)
  does not specify its own expiration time.
  Only returned in `GET` requests if `view=FULL` is set.
  </pre>
  
  <code>.google.protobuf.Duration default_expiration = 105;</code>