REST bad code 422, change to 400

[essen]

Topic.

[bullno1]

I think the issue is differentiating between entity being syntactically incorrect vs semantically incorrect. The current handler can only return false on error. How about we extend that to {false, Reason}? {false, syntax} or {false, format} would return 400 but {false, semantic} or {false, processing} would return 422.

Edit: I'm not suggesting we accept 2 reasons for each code, I just can't decide on a proper name.

[essen]

422 is a webdav code, it is not defined for HTTP and clients will interpret it as 400 anyway.

[essen]

Done!