Fixing issue #1592

[fmmmlee]

As cqjason describes in issue #1592, the behavior of JsonTreeWriter.name() is inconsistent with the method it overrides in its parent JsonWriter. When calling JsonWriter.name(null), a NullPointerException is thrown, while calling JsonTreeWriter.name(null) does not throw an exception, leading to a potentially misleading IllegalStateException when calling JsonTreeWriter.value() later in execution.

To resolve this, I just copied the null check from lines 385-387 of JsonWriter.

Edit: I had made a few style changes to the design document on this fork, but reverted them in order to keep the changes issue-related.

[Marcono1234]

Would it be possible to force push only 49280df or squash the commits? I assume the maintainers here would like to not include commits which are then reverted in a later commit.

[fmmmlee]

I believe maintainers have the option to squash when merging a pull request, so it only shows up as a single commit. I don't think they can be squashed before merging, though; only when performing the merge.

Edit: Closed issue and opened #1623 that only has the relevant commit.