ietf-*-types missing from repo for IOS XE < 16.5.1 and IOS XR < 6.0.2, 6.1.1

[remingtonc]

The ietf-inet-types.yang file appears to be missing from:
https://github.com/YangModels/yang/tree/master/vendor/cisco/xe/1631
https://github.com/YangModels/yang/tree/master/vendor/cisco/xe/1632
https://github.com/YangModels/yang/tree/master/vendor/cisco/xe/1641

This yields incomplete parsing.

EDIT:
The types are also not in the folders corresponding to IOS XR versions < 6.0.2. Revised title. This seems to be understood per IOS XE check and IOS XR check. Are items pre-"check"able reasonable to parse? Or something to ignore?

EDIT:
Also missing in IOS XR 6.1.1.

EDIT:
Other ietf-*-types modules are missing in various IOS XE repos as well. ietf-yang-types for instance. Have not validated other repos.

[einarnn]

In the earliest commits of per-OS/platform YANG models we (Cisco) didn't replicate either IETF or OpenConfig models that may have been supported by the platform. We also didn't provide sample XML capability files. The lack of inclusion of the specific versions of dependencies used in a specific OS release turned out to be a mistake that we rectified in subsequent releases. However, we never went back to patch the earlier releases to include the specific 3rd party dependencies.

If you want to put together a PR with the missing models for earlier releases, that would be most welcome!

[remingtonc]

Going to let this hang in limbo for a bit as I'm uncertain how to determine what models were present in earlier releases other than this repo.

[einarnn]

The obvious answer is to spin up an image (probably XRv or XRv 9000 would be fine) to determine this. But this is really a Cisco issue, not an issue for this repo as such, so closing for now.