@Documented
 @Retention(value=RUNTIME)
 @Target(value=METHOD)
public static @interface DoFn.FinishBundle
DoFn.FinishBundleContext, then it will be
       passed a context object for the current execution.
   DoFn.BundleFinalizer, then it will be passed a
       mechanism to register a callback that will be invoked after the runner successfully
       commits the output of this bundle. See Apache Beam Portability API: How to
       Finalize Bundles for further details.
 Note that @FinishBundle is invoked before the runner commits the output
 while bundle finalizer callbacks are invoked after the runner
 has committed the output of a successful bundle.