Fixes for upstream

minor cleanups which supposed not to change logic, but
make code cleaner.
The comment above the changed line explicitly says that they're creating a new String (via `new String("NULL")`) to avoid interning.

Either it's not okay to change to be just `"NULL"` or the comment above it should be removed as well.

I've got to read through the rest of the code a bit more to give an opinion, but if someone else is more familiar with why it's defined as such, please chime in.