@Override
    public String getMetadataKey(MetaField metaField) {
        String metadataKey;
        switch (metaField) {
            case TABLE_NAME:
                metadataKey = "table_name";
                break;
            case COLLECTION_NAME:
                metadataKey = "collection_name";
                break;
            case SCHEMA_NAME:
                metadataKey = "schema_name";
                break;
            case DATABASE_NAME:
                metadataKey = "database_name";
                break;
            case OP_TS:
                metadataKey = "op_ts";
                break;
            case DATA_DEBEZIUM:
            case DATA_BYTES_DEBEZIUM:
                metadataKey = "meta.data_debezium";
                break;
            case DATA_CANAL:
            case DATA_BYTES_CANAL:
                metadataKey = "meta.data_canal";
                break;
            default:
                throw new UnsupportedOperationException(String.format("Unsupport meta field for %s: %s",
                        this.getClass().getSimpleName(), metaField));
        }
        return metadataKey;
    }
the primary key must be "_id"

@see <a href="https://ververica.github.io/flink-cdc-connectors/release-2.1/content/connectors/mongodb-cdc.html#">MongoDB CDC Connector</a>
inlong-sort/sort-common/src/main/java/org/apache/inlong/sort/protocol/node/extract/MongoExtractNode.java