public static @interface DoFn.StartBundle
DoFn.StartBundleContext, then it will be
passed a context object for the current execution.
PipelineOptions, then it will be passed the
options for the current pipeline.
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.