private Map<String, String> mergeComment(Map<String, String> metadata, String comment) {
        Map<String, String> ret = Maps.newHashMap(metadata);
        if (metadata.containsKey("comment")) {
            throw new CatalogException("Database properties should not contain key: 'comment'.");
        }

        if (!StringUtils.isNullOrWhitespaceOnly(comment)) {
            ret.put("comment", comment);
        }
        return ret;
    }
Append a new level to the base namespace
inlong-sort/sort-flink/sort-flink-v1.15/sort-connectors/iceberg/src/main/java/org/apache/inlong/sort/iceberg/FlinkCatalog.java