feat(plugin): optional fields for oneof properties

[Larkooo]

addresses issue #548

[boukeversteegh]

I think it might be worthwhile to add a simple test that only instantiates an object of a type with one-of fields, and omits a field.

If we ever break this feature, the TS file won't compile.

for example, in oneof-properties-tests:

  it('allows omitting fields', () => {
      let msg: PleaseChoose = {
         name: 'foo',
      }
  });

[SteveVaknin]

Hi @Larkooo, very strong work!
This can be super useful.

Are you planning to continue working on it?

[scott-lc]

Just ran into this issue today. Anything I can do to help get the PR merged?

[stephenh]

@scott-lc yeah, would be great if you wanted to pick this up; just scanning the PR, I think the issues would be to:

a) See the PR comment about running yarn proto2bin to hopefully remove all of the *.bin files as changed files in the PR

b) Remove the yarn-error.log from the PR

c) Rebase the PR onto the latest main

d) Update one of the integration-tests/* projects to have a schema that reproduces the issue and has a test case that shows the codegen output continues to work as you expect; i.e. @boukeversteegh had suggested this has a starting place:

https://github.com/stephenh/ts-proto/blob/8769ef2ad01d53edc2d373201afeab8ca7403885/integration/oneof-properties/oneof-properties-test.ts

Thanks!