@Override
                public Object read(SourceRecord record) {
                    Struct value = (Struct) record.value();
                    Struct source = value.getStruct(Envelope.FieldName.SOURCE);
                    return TimestampData.fromEpochMillis(
                            (Long) source.get(AbstractSourceInfo.TIMESTAMP_KEY));
                }
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