Add Error Codes annotation for Operations to Core

[JefWight]

Similar to the comments that can be placed on elements in C#, we'd like to be able to document known / expected Error Codes that can be returned from an Operation. This allows us to be able to communicate what types of errors a client may expect to receive as well as a blurb about how they can handle it.

[ralfhandl]

Hi Jeff,

I'd like to continue this discussion on the odata-comment mailing list.

Thanks in advance!
--Ralf

[ralfhandl]

See https://lists.oasis-open.org/archives/odata-comment/201510/msg00006.html

[ralfhandl]

Issue ODATA-884 - Add term ErrorCodes to describe possible codes in error messages (public comment c201510e00019) has been created.