Note the idea would be to apply this to the Histogram point after PR #272.

This is stale and we may revisit this topic after other histogram work is finished.

I modified this PR to use proto3 "optional" which means to use explicit presence, see this document:
https://chromium.googlesource.com/external/github.com/protocolbuffers/protobuf/+/refs/heads/master/docs/field_presence.md

The build says:

opentelemetry/proto/metrics/v1/metrics.proto: This file contains proto3 optional fields, but --experimental_allow_proto3_optional was not set.

I believe with open-telemetry/opentelemetry-collector#4929 this is now fully unblocked. @jmacd please rebase the branch

Thank you @codeboten!

@bogdandrutu please review

@jmacd @codeboten as in any ideal world, we should start with fixing a bug first #336 than adding new functionality. Should we merge the optional sum?

Either one is fine with me @bogdandrutu, I don't think I have permissions to push changes to #336 to unblock the PR 😬

Let’s fix that first. Maybe clone that PR and open a new one with necessary changes.

@bogdandrutu see #366

@codeboten I want to do a release #367 then start using this in collector to prove everything is fine, then will merge this.

I modified this PR to use proto3 "optional" which means to use explicit presence, see this document: https://chromium.googlesource.com/external/github.com/protocolbuffers/protobuf/+/refs/heads/master/docs/field_presence.md

This is really annoying. It means opentelemetry isn't build-able or usable on ubuntu bionic with upstream provided packages.