Revert #410

[stevvooe]

#410

omitempty has nothing to do with REQUIRED vs OPTIONAL fields.

[wking]

Cross-linking earlier discussion in #553.

[philips]

@stevvooe in #553 you are saying we should omitempty everywhere. So you would be ok with #410 if it was just doing omitempty but didn't mention optional/required?

[stevvooe]

@philips We should not emit fields that contain zero-values. It's wasteful and distracting.

There are certain exceptions, but, in general, use of omitempty should be the rule.

[wking]

On Mon, Feb 06, 2017 at 02:20:19PM -0800, Stephen Day wrote: There are certain exceptions, but, in general, use of `omitempty` should be the rule.

If the exceptions are “when the zero-value is valid” (based on [1]). Then: $ git grep '^ [A-Z]' specs-go/ | grep -v omitempty turns up the following fields (in master, as of ed18de1) which could pick up omitempty: * RootFS.type (REQUIRED, MUST be ‘layers’) * RootFS.DiffIDs (REQUIRED, corresponsed to manifest's ‘layers’ which REQUIRES at least one entry with #407 in flight). * Image.Architecture (REQUIRED, empty string not explicitly illegal, but it probably should be). * Image.OS (REQUIRED, empty string not explicitly illegal, but it probably should be). * Descriptor.Digest (REQUIRED, empty string missing algorithm, separator, and hash). * ImageLayout.Version (REQUIRED, empty string will never be valid unless image-spec cuts an empty-string release). * Manifest.Layers (REQUIRES at least one entry with #407 in flight). * Platform.Architecture (REQUIRED, empty string not explicitly illegal, but it probably should be). * Platform.OS (REQUIRED, empty string not explicitly illegal, but it probably should be). * Versioned.SchemaVersion (REQUIRED, must be 2). I still don't see a point to adding omitempty to a REQUIRED property, but if that's what you want to do, the above properties are probably what you'd do it to. Manifest.Manifests is REQUIRED, although without a requirement to have at least one value I'm not sure why. In any case, as long as it's required and allows an empty array we don't want ‘omitempty’ there. [1]: #553 (comment)

[stevvooe]

I'm sorry but I misread #410.

For the most part, we should be using omitempty except in specific circumstances.

Closing this now. Apologies.