def __getitem__(self, item):
        """
        Warn users that a ``KeyError`` can be expected when a
        mising key is supplied. Ref python/importlib_metadata#371.
        """
        res = super().__getitem__(item)
        if res is None:
            _warn()
        return res

        Warn users that a ``KeyError`` can be expected when a
        mising key is supplied. Ref python/importlib_metadata#371.
        
product/gradle-plugin/src/main/python/setuptools/_vendor/importlib_metadata/_adapters.py