Call skipChildren for nested object

[tedyu]

What changes were proposed in this pull request?

In jsonObjectKeys, we should call skipChildren() properly for nested object.

Why are the changes needed?

Currently if jsonParser.currentName() is null, the loop is terminated. We should relocate the current name check inside the loop.

Does this PR introduce any user-facing change?

No.

How was this patch tested?

Was this patch authored or co-authored using generative AI tooling?

No.