Invoked after normal completion or failure.

Invoked when failure is signaled from upstream. If this method throws an exception, then onError is immediately propagated downstream. If this method completes normally then OnTermination(Exception) is invoked as a final step, passing the original cause.

Invoked for each element to produce a (possibly empty) sequence of output elements.

Invoked before the Transformer terminates (either normal completion or after an onError) to produce a (possibly empty) sequence of elements in response to the end-of-stream event. This method is only called if OnError(Exception) does not throw an exception. The default implementation of OnError(Exception) throws the received cause forcing the failure to propagate downstream immediately.