Upsert

[aip-dev]

Upsert

[lukesneeringer]

Some additional notes:

• The current style guide (and therefore AIP-134) currently say to use Update. (This seems counter-intuitive so I am not making an argument here -- changing it seems fine to me.)
• Often in upsert there is a concept of "only set this field to the thing I provided if it was not already set to something else". We probably need a mechanism for this. (Perhaps google.protobuf.FieldMask default_mask?)
• Do we allow implementing this method instead of Create and/or Update? (Proposal: No, should-level -- require justification.)
• The name "Upsert" is a tad unfortunate since we use "Create" and not "Insert" as our creation verb. However, the term "Upsert" is so well known that I am disinclined to challenge this. It seems better than "Create Or Update".

[apasel422]

Is there anything left here that isn't covered by https://google.aip.dev/134#create-or-update?