MessageDigest & threadSafety: duplicate hash values on large concurrent processing (Spark-UDF)

Issue: MessageDigest was used as a singleton for this UDF exposed function. As MessageDigest is not threadSafe, it caused duplicate hash values when a large volume of concurrent data was processed.

Solution: So changed the logic to initialize the object for each call.

So see below the old and new approaches highlighted below (obsolete code can be removed) 

Further reference:

how-to-solve-non-serializable-errors-when-instantiating-objects-in-spark-udfs/

need-thread-safe-messagedigest-in-java