Take beta declaration serious or remove it.

[Oberon00]

#103 declared large parts of the protocols as beta, but purely cosmetic yet breaking changes like #120 were still incorporated. What's the definition of beta, this repository is following?
(I think our official definition is a bit over the top https://github.com/open-telemetry/community/blob/master/maturity-matrix.yaml#L43-L49)

[tigrannajaryan]

I agree, we should take beta declaration seriously. Note that we are still allowed to make braking changes but very infrequently. According to API maturity level definitions:

"beta" maturity APIs should not introduce backwards-incompatible changes
more than once every three months; and when those changes are introduced, the
authors will make a best effort to provide compatibility bridges.

Given that there are no existing OTLP implementations yet arguably we are still OK with making changes, but I agree, we should all begin to respect the definition of "beta" or agree that it is too early and remove the label. The later will have ramifications: work that depends on protocol being "beta"-stable will be halted.

[SergeyKanzhelev]

should we revert the #120 than or keep it? I also filed an issue that the change may not be great for interoperability

[Oberon00]

Good question. Actually, I think a (beta) release should be tagged (currently there are no tags at all https://github.com/open-telemetry/opentelemetry-proto/tags), otherwise the beta declaration is either meaningless, or just states that the next tag will be beta, or every commit counts as release.

[SergeyKanzhelev]

Totally agree. Tag would be very helpful. @bogdandrutu revert or keep the change?

[tigrannajaryan]

I suggest we keep #120. It is done and already used by dependent repos, reverting is worse.

[Oberon00]

So the action item here is to tag a release?

[Oberon00]

Since a release was tagged now, are we fine with keeping the beta-"promise" in the README?

CC @bogdandrutu

[bogdandrutu]

What does "beta promise" means?

[Oberon00]

@bogdandrutu See @tigrannajaryan's comment: #128 (comment)

[tigrannajaryan]

I think we recently made a sufficient efforts to be serious about maturity declarations. I suggest that we close this issue.