Your (groovy?) code does not tell me how you use the above configuration to create your cache.
I'm surprised redefining the default cache configuration actually worked after having started the cachemanager.
I would like to make this functional again (supposing I find out what is causing the issue): however the "fluent()" configuration was deprecated since 5.1 and the new builder configuration should be used.
Well, I changed my configuration to the new 5.2 API. Wasn't too hard.
I think it's good you're cleaning up the configuration API but I would suggest you get rid of the old one(s?) more aggressively -- the Ehcache guys have on occasion removed deprecated methods and so code breaks immediately when updating. In my case, the code ran but didn't work.