def get_output_mapping(self) -> Dict[str, str]:
        """
        Return a mapping between destination files as they would be produced by the
        build (dict keys) into the respective existing (source) files (dict values).
        Existing (source) files should be represented as strings relative to the project
        root directory.
        Destination files should be strings in the form of
        ``"{build_lib}/destination/file/path"``.
        """

        Return a mapping between destination files as they would be produced by the
        build (dict keys) into the respective existing (source) files (dict values).
        Existing (source) files should be represented as strings relative to the project
        root directory.
        Destination files should be strings in the form of
        ``"{build_lib}/destination/file/path"``.
        
product/gradle-plugin/src/main/python/setuptools/command/build.py