@Override
                public Object read(SourceRecord record) {
                    return StringData.fromString(
                            getMetaData(record, MongoDBEnvelope.NAMESPACE_DATABASE_FIELD));
                }
Defines the supported metadata columns for {@link MongoDBTableSource}.
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/mongodb-cdc/src/main/java/org/apache/inlong/sort/cdc/mongodb/table/MongoDBReadableMetadata.java