The HL7AcknowledgmentGenerator is setting the CamelMllpAcknowledgement message header, but this should be an exchange property.
This is "hangover" from when this class was an internal/implementation class. Since I moved it and made it generally available for use, it should be setting the exchange property so that the acknowledgement will be delivered.
As currently written, the user will have to copy the message header to the exchange property for it to be used. If this isn't done, the component will generate a new acknowledgement.