public static File getFile(URL resourceUrl) throws FileNotFoundException {
        return getFile(resourceUrl, "URL");
    }
Resolve the given resource URL to a {@code java.io.File},
i.e. to a file in the file system.

@param resourceUrl the resource URL to resolve
@return a corresponding File object
@throws FileNotFoundException if the URL cannot be resolved to
                              a file in the file system
src/main/java/spark/utils/ResourceUtils.java