QueueAttributeName is used instead of missing MessageAttributeName

[EduardSergeev]

QueueAttributeName is used to represent a set of "would be" MessageAttributes.
The correct set of MessageAttributes is as per comments:

• All - returns all values.
• ApproximateFirstReceiveTimestamp - returns the time when the message was first received from the queue (epoch time in milliseconds).
• ApproximateReceiveCount - returns the number of times a message has been received from the queue but not deleted.
• SenderId - returns the AWS account number (or the IP address, if anonymous access is allowed) of the sender.
• SentTimestamp - returns the time when the message was sent to the queue (epoch time in milliseconds).

Looks like Amazon documentation is incorrect since it enumerates QueueAttributes as valid values for MessageAttributes.

[brendanhay]

I believe this is the same issue raised upstream: boto/botocore#602

[brendanhay]

Short term, I may just construct an override to correct the enum branches.

[brendanhay]

Leaving this open due to other potential issues. Really needs to be fixed upstream, but in the meantime I'll add overrides as I become aware of the cases.