Critical Description
The unmarshal code that deals with reading in tight marshaled long values that have been compacted to a less than eight bytes incorrectly reads these values as signed instead of unsigned as it should leading to incorrect data in unmarshalled objects.
This can manifest when a message is received with a MessageId that has a producer sequence ID value greater than the max signed value of an int or short. The Ack to the broker would contained an unknown message ID and lead to an error.