public static MapNullKeyMode getMapNullKeyMode(String mapNullKeyMode) {
        switch (mapNullKeyMode.toUpperCase()) {
            case MAP_NULL_KEY_MODE_FAIL:
                return MapNullKeyMode.FAIL;
            case MAP_NULL_KEY_MODE_DROP:
                return MapNullKeyMode.DROP;
            case MAP_NULL_KEY_MODE_LITERAL:
                return MapNullKeyMode.LITERAL;
            default:
                throw new TableException(
                        String.format(
                                "Unsupported map null key handling mode '%s'. Validator should have checked that.",
                                mapNullKeyMode));
        }
    }
Creates handling mode for null key map data.

<p>See {@link #MAP_NULL_KEY_MODE_FAIL}, {@link #MAP_NULL_KEY_MODE_DROP}, and {@link
#MAP_NULL_KEY_MODE_LITERAL} for more information.
inlong-sort/sort-formats/format-common/src/main/java/org/apache/inlong/sort/formats/base/TextFormatOptionsUtil.java