def _normalize_requires(self):
        """Make sure requirement-related attributes exist and are normalized"""
        install_requires = getattr(self, "install_requires", None) or []
        extras_require = getattr(self, "extras_require", None) or {}
        self.install_requires = list(map(str, _reqs.parse(install_requires)))
        self.extras_require = {
            k: list(map(str, _reqs.parse(v or []))) for k, v in extras_require.items()
        }
Make sure requirement-related attributes exist and are normalized
product/gradle-plugin/src/main/python/setuptools/dist.py