From 395c8422fe90080314c7d9b4114d701a0c049e1f Mon Sep 17 00:00:00 2001
From: Tigran Najaryan <4194920+tigrannajaryan@users.noreply.github.com>
Date: Wed, 19 Apr 2023 20:31:44 -0400
Subject: [PATCH] Clarify how additive changes are handled (#455)

This PR explicitly lists the additive changes allowed and adds
a requirement that such additive changes must be accompanied by
interoperability explanation when necessary.

This is a subset of https://github.com/open-telemetry/opentelemetry-proto/pull/432
that contains other guarantees that we did not yet agree to.
I believe this particular subset is necessary regardless of
what we decide about #432.
---
 README.md | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/README.md b/README.md
index 29fa0ed61..5a8a1710d 100644
--- a/README.md
+++ b/README.md
@@ -66,6 +66,19 @@ The following changes are allowed:
 Note that none of the above allowed changes affects the binary wire representation or the
 JSON wire representation.
 
+The following additive changes are allowed:
+
+- Adding new fields to existing messages.
+- Adding new messages or enums.
+- Adding new choices to existing enums.
+- Adding new choices to existing oneof fields.
+- Adding new services.
+- Adding new methods to existing services.
+
+All the additive changes above must be accompanied by an explanation about how
+new and old senders and receivers that implement the version of the protocol
+before and after the change interoperate.
+
 No guarantees are provided whatsoever about the stability of the code that
 is generated from the .proto files by any particular code generator.