protected File getFileForLastModifiedCheck() throws IOException {
        return getFile();
    }
Determine the File to use for timestamp checking.
<p>The default implementation delegates to {@link #getFile()}.

@return the File to use for timestamp checking (never {@code null})
@throws IOException if the resource cannot be resolved as absolute
                    file path, i.e. if the resource is not available in a file system
src/main/java/spark/resource/AbstractResource.java