Alternative to +SETALL permissions requirement on IBM MQ Adapter connections using -EQN

IBM MQ Adapter connections often use the -EQN facility to designate an alternate queue from the input -QN so that error messages do not get stuck in the input queue and interfere with message processing over time.

The use of -EQN requires the +SETALL permission on the IBM MQ server for the given itxuser.  Presumably this is because the -EQN function is using the full -HDR syntax on PUT to preserve all current MQMD settings.  E.g., the message is being copied as is instead of being re-created.

Unfortunately, our organization has identified +SETALL as a security risk because the so granted itxuser has the same effective authority level as the MQ administrators.  This elevated access needs to be removed, but in doing so, the -EQN setting no longer works.

In discussions with IBM Support the implication was that the current usage of -EQN cannot be altered due to impacts to other clients. 

Therefore, I propose a new optional command be added to the IBM MQ Adapter to be used in conjunction with the -EQN command.  Essentially, the new command tells -EQN to either continue using the default behavior of -HDR (preserving current MQMD settings), or to allow -DH on -EQN (effectively putting a new message).

This means that users that do not want to use the flag will continue to have the default behavior and require no code changes as long as they accept the usage of +SETALL permissions.  For those that cannot allow the +SETALL permissions, the new command would allow -EQN to continue to work with a minor update to the IBM MQ Adapter connection settings.  While this does create a new message and deletes the current MQMD, our organization has decided this is an acceptable loss.  In general, we are not exploiting those header settings for reprocessing anyway, but rather using message content.