> Good API design dictates that you should be flexible as to what you accept and strict about what you serve. Being flexible doesn't really break anything.

Do you have a source on that? I am not sure I agree. My gripe is with HOCON that accepts so many formats that after a while you have no idea what it is you are actually writing. You can have a conf file with 5 different formats of the same type of setting. Probably added to by 5 different developers.

I'd rather have it throw an error in my face when I don't adhere.