protected MetadataConverter[] getMetadataConverters() {
        if (metadataKeys.isEmpty()) {
            return new MetadataConverter[0];
        }

        return metadataKeys.stream()
                .map(
                        key -> Stream.of(MongoDBReadableMetadata.values())
                                .filter(m -> m.getKey().equals(key))
                                .findFirst()
                                .orElseThrow(IllegalStateException::new))
                .map(MongoDBReadableMetadata::getConverter)
                .toArray(MetadataConverter[]::new);
    }
Metadata that is appended at the end of a physical source row.
inlong-sort/sort-flink/sort-flink-v1.15/sort-connectors/mongodb-cdc/src/main/java/org/apache/inlong/sort/mongodb/MongoDBTableSource.java