Document server side contract for partial updates

The requirement of the server is to use HTTP PATCH method together with ETag header and partially updated content.

The server understands HTTP PATCH requests with IETF JSON Patch and JSON Merge Patch (draft) formats, where the appropriate format is specified by Content-Type header defined by given format.

The server supports automatic conflict resolution mode and uses appropriate response status codes and response body in case of merge with:

• No conflict. 200 OK, No response body.
• Resolved conflict. 200 OK, Response body in format json-patch or json-merge-patch as specified by Accept header.
• Unresolvable conflict. 409 Conflict, Full version in response.