How do you start a jupyter kernel with custom ports?

I am trying to start a jupyter kernel like this:

jupyter-kernel \
       --ip=0.0.0.0 \
       --KernelManager.control_port=56406 \
       --KernelManager.hb_port=56407 \
       --KernelManager.iopub_port=56408 \
       --KernelManager.shell_port=56409 \
       --KernelManager.stdin_port=56410

It starts, and I see this output:

[KernelApp] Starting kernel 'python3'
[KernelApp] Connection file: /Users/jkitchin/Library/Jupyter/runtime/kernel-892382b5-8115-44ba-95cd-d8172ba848ac.json

however, the kernel json contains:

cat /Users/jkitchin/Library/Jupyter/runtime/kernel-892382b5-8115-44ba-95cd-d8172ba848ac.json
{
  "shell_port": 55505,
  "iopub_port": 55506,
  "stdin_port": 55507,
  "control_port": 55509,
  "hb_port": 55508,
  "ip": "0.0.0.0",
  "key": "0a163fda-2b4963c994abc4277bdf58fa",
  "transport": "tcp",
  "signature_scheme": "hmac-sha256",
  "kernel_name": ""
}

which do not match the ports I specified. Am I missing something to make this happen?

Answering my own question here. It turns out the ports were not configurable at the command line even though the documentation suggested they were. This was fixed in https://github.com/jupyter/jupyter_client/pull/956, and now it should work.