ipyparallel for ipykernel -- deprecated or what?

There are a few files in the source tree where importing them triggers a warning they're deprecated and one should use ipyparallel.

But ipyparallel is mentioned as a test dep in setup.py, and not as a dep in pyproject.toml.

And CHANGELOG.md and a few but reports here mention ipyparallel itself as being deprecated.

What is the status of ipyparallel in ipykernel?