def json(self):
        """
        Convert PackageMetadata to a JSON-compatible format
        per PEP 0566.
        """

        def transform(key):
            value = self.get_all(key) if key in self.multiple_use_keys else self[key]
            if key == 'Keywords':
                value = re.split(r'\s+', value)
            tk = key.lower().replace('-', '_')
            return tk, value

        return dict(map(transform, map(FoldedCase, self)))

        Convert PackageMetadata to a JSON-compatible format
        per PEP 0566.
        
product/gradle-plugin/src/main/python/setuptools/_vendor/importlib_metadata/_adapters.py