MQ v7 client jars upgrade on WAS 6, 6.1 or 7.0

We had a lot of issues here at my customer when we tried upgrading the client jars for MQ from v6 to v7.0.1.2.
You know how MQ client jars though packaged with WAS can be externalized and you could have WAS 6.0.x updated to use MQ v7 client jars.

Problems :

1. Unable to put messages on an MQ Queue.
2. Unable to retrieve messages via an MDB.
3. MQ v7 client jars added a new behavior where if no ID was specified, it would use the WAS process running user ID as the ID for authentication on the MQ Qmgr. With MQ V6 client jars a blank ID was passed, if no ID was specified. MQ QMgr runs under an MCA user ID and if a blank was encountered it would authenticate using the MCA user ID and it would work. However , since MQ v7 client jars specified a fixed ID, the WAS running process user ID need to be in the mqm group for it to be authenticated on the Qmgr. This was a problem.
4. Issues serializing a JMS Message originated from MQ v6 Qmgr and delivered via the MQ v7 client jars to WAS.

Easy fix:

1. Most customers use a component managed auth alias configured on their MQ Queue Connection factories, but this customer viewed component managed auth aliases as a security hole and wanted it to work with container managed auth aliases only.
2. Include the WAS running process User id in the mqm group.

Resolution:

IZ72486 - A new APAR was created that rolled back the blank ID behavior on the MQ v7 client jars. So now a blank ID would stay blank.
( this will be included after 7.0.1.3)
PMR 05950,122,000 - IZ81411 - A new APAR that allowed some of the MQ v6 custom headers in the JMSObject to be serialized in the MQ v7 client jars so that they can be passed over the wire. ( this will be included later, maybe after 7.0.1.4).

The best and easiest way to get the fixes was to go by the MQ client jar version. Fixers asked for WAS were getting garbled up because support tended to match a WAS version with the appropriate MQ version as I mentioned above that the MQ client jars are bundled along with the product.