Allow proceeding zeros in factional seconds

[david-waltermire]

Committer Notes

Allow proceeding zeros in factional seconds.

This addresses the issue identified in usnistgov/liboscal-java#141 and usnistgov/OSCAL#1774.

All Submissions:

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you squashed any non-relevant commits and commit messages? [instructions]
• Do all automated CI/CD checks pass?

Changes to Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your core changes, as applicable?
• Have you included examples of how to use your new feature(s)?
• Have you updated all website](https://pages.nist.gov/metaschema) and readme documentation affected by the changes you made? Changes to the website can be made in the website/content directory of your branch.

[aj-stein-nist]

I am good with the change, I would recommend adding the example 2019-09-28T23:00:00.0Z or one with more trailing zeros so we can copy-paste the examples in the datatypes page so I can use things like regex101.com to make testing quicker.

We also want to optionally consider change the 60 second examples because those don't validate (such at 60 in 2019-12-31T23:59:60Z because of how seconds work), but that is minor. Otherwise, this looks good!

[nikitawootten-nist]

@wendellpiez and I generated the OSCAL schemas and have confirmed that this fixes usnistgov/OSCAL#1774. Looks good to us!

[wendellpiez]

We reviewed and validated the regex (and learned many things about the containers/distro while doing so) thanks for the work

[nikitawootten-nist]

Could you add an example to the following schema validation test: https://github.com/usnistgov/metaschema/blob/main/test-suite/schema-generation/datatypes/datatypes-datetime_test_valid_PASS.json