0.7.0: sphinx warnings

Sphinx shows some warnings on generate sphinxcontrib-openapi modiule documentation

[tkloczko@barrel openapi-0.7.0]$ SETUPTOOLS_SCM_PRETEND_VERSION=0.7.0 /usr/bin/python3 setup.py build_sphinx -b man --build-dir build/sphinx
running build_sphinx
Running Sphinx v4.1.2
making output directory... done
building [mo]: targets for 0 po files that are out of date
building [man]: all manpages
updating environment: [new config] 1 added, 0 changed, 0 removed
reading sources... [100%] index
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
<openapi>:1: WARNING: Problem in http domain: field is supposed to use role 'obj', but that role is not in the domain.
looking for now-outdated files... none found
pickling environment... done
checking consistency... done
writing... sphinxcontrib-openapi.1 { } done
build succeeded, 17 warnings.

Start by rerunning SETUPTOOLS_SCM_PRETEND_VERSION=0.7.0 /usr/bin/python3 setup.py build_sphinx -b man --build-dir build/sphinx and inspect the generated Sphinx warnings for the OpenAPI documentation. Trace the HTTP-domain field handling reported in the output; done means the documentation build completes without these warnings.