[Bjartr]

Reading section III, I see it specifically calls out the value in avoiding on-disk property files and named per-environment groupings of properties as non-scalable anti-patterns. I don't know whether or not I agree with that, but I am curious why you're claiming to be inspired by that section when, by and large, the only thing that seems to align with what's described in section III is not hardcoding the property values directly in code, which isn't really specific to the twelve factor methodology.

[jeyjeyemem]

You can still strictly adhere to section III if you choose to - by only loading the environment variables, but Externalized Properties allows more than that if needed.

By using ExternalizedProperties instead of direct System.getenv() you get other useful features such as automatic conversions, variable expansion, and processing (e.g. automatic decryption/automatic base64 decode, etc)