When using the `AsyncItemProcessor` and `AsyncItemWriter`, business
exceptions that occur during the process phase are hidden by an
`ExecutionException` that is returned wrapping the originally thrown
exception in the `AsyncItemWriter`. In this commit, we now unwrap any
`ExecutionException` that is returned and throw the cause. Debug
logging is also added to allow the logging of the original exception as
well.
Resolves BATCH-2386
cfad543a63