[sdf] Fix Sdf_Children<ChildPolicy>::Find to return correct value

[nvidia-jomiller]

In most cases, Sdf_Children::Find would return the incorrect value of 0 instead the size of _childNames. This would incorrectly index into the first element when a match was not found

Description of Change(s)

Link to proposal (if applicable)

Fixes Issue(s)

Checklist

[x] I have created this PR based on the dev branch

[x] I have followed the coding conventions

[x] I have added unit tests that exercise this functionality (Reference:
testing guidelines)

[x] I have verified that all unit tests pass with the proposed changes

[x] I have submitted a signed Contributor License Agreement (Reference:
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[jesschimein]

Filed as internal issue #USD-10583

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[jesschimein]

/AzurePipelines run

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[sunyab]

Hey @nvidia-jomiller,

I'm not quite seeing the bug you mentioned in your PR description. Prior to your change, in the case where the given key isn't found, the index i would have been incremented to _childNames.size() and then returned. The test case you added worked both with and without your change. AFAICT, the only functional change is that in the failed verify case we now return _childNames.size() instead of 0.

Am I missing something?

[nvidia-jomiller]

Hey @sunyab , thanks for taking a look!

The change was mostly facilitated by another task but yeah, now that I read through it line by line I see functionally it's equivalent. What I was mostly going from is checks in SdfChildrenView and code docs in Sdf_Children. I didn't see any tests specifically testing it so I modified and added a test. I think this might just be a readability thing where I was expecting to see _childNames.size() returned. But I'm happy to close this out

[sunyab]

Ok, thanks for confirming! Please leave this open for now, if nothing else I think we can merge in the test since more tests are always appreciated.