*
 * Character mapping files contain mapping rules in the format:
 * input1,input2,... => output
 */
public class CharMappingFile extends DictionaryFile<CharMappingItem> {
    /** Logger instance for this class. */
    private static final Logger logger = LogManager.getLogger(CharMappingFile.class);

    /** Type identifier for character mapping dictionaries. */
    private static final String MAPPING = "mapping";

        verifyToken(() -> uploadpage(form.dictId));
        return charMappingService.getCharMappingFile(form.dictId).map(file -> {
            try (InputStream inputStream = form.charMappingFile.getInputStream()) {
                file.update(inputStream);
            } catch (final IOException e) {
                logger.warn("Failed to process a request.", e);