Howto: I want to get aplain list with all domain names

[marneu]

Ubuntu: 20.04
Python: 3.8
Version: fresh git+https://github.com./derJD/python-mailcow.git (python-mailcow-1.0.5.dev4+g802abec)

Imho I was trying:
mailcow domain get --all --fields 'domain_name'
expecting to receive a list with all domain names only.
The result is :

Traceback (most recent call last):
  File "/usr/local/lib/python3.8/dist-packages/prettytable/prettytable.py", line 353, in _validate_field_name
    assert (val in self._field_names) or (val is None)
AssertionError

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/sbin/mailcow", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.8/dist-packages/mailcow/cli.py", line 86, in main
    print(table.get_string(fields=fields))
  File "/usr/local/lib/python3.8/dist-packages/prettytable/prettytable.py", line 1130, in get_string
    options = self._get_options(kwargs)
  File "/usr/local/lib/python3.8/dist-packages/prettytable/prettytable.py", line 846, in _get_options
    self._validate_option(option, kwargs[option])
  File "/usr/local/lib/python3.8/dist-packages/prettytable/prettytable.py", line 246, in _validate_option
    self._validate_all_field_names(option, val)
  File "/usr/local/lib/python3.8/dist-packages/prettytable/prettytable.py", line 360, in _validate_all_field_names
    self._validate_field_name(name, x)
  File "/usr/local/lib/python3.8/dist-packages/prettytable/prettytable.py", line 355, in _validate_field_name
    raise Exception("Invalid field name: %s!" % val)
Exception: Invalid field name: d!

What is the expectation of the --fields parameter?