Sphinx configuration parser issues warning when using a list for the plantuml command

[software-opal]

I'm trying to use a list as the plantuml command(see snip below), and Sphinx is issuing a warning about the type not matching the default. This is a problem for me as I upgrade all warnings to errors.

conf.py:

import sys
...
extensions = [
    "sphinxcontrib.plantuml",
]
plantuml = [sys.executable, './plantuml_wrapper.py']
...

It appears that Sphinx 1.4.? added support for other types in sphinx/sphinx#2033 (you can see the versions that the PR is included in here). It should just be a matter of adding the type hints to the add_config_value calls in the setup function.