Lesson learned. I was using the aws-java-sdk-1.4.x.jar file for my (in this case coldfusion) app. However, doing a routine update of my code, I downloaded the 1.8 version of this file, suddenly started getting these ClientConfiguration errors.
In short, the way amazon has started accepting it’s configuration parameters has completely changed. I’m not going to retool my stuff right now, but will have to. Anyway, just in case you come across this error, one solution is to go back to the 1.4 or other whatever version you were using before.
While 1.4 is not available, gitHub has a variety of versions for you to download, unpack and try, just in case you’ve no longer have access to your old version.