private boolean disableSwitch() {
        return !switchAppendUpsertEnable || multipleSink || incrementalFieldIndex == DEFAULT_META_INDEX;
    }
disable switch when the switch property is disabled
or the sink is multiple sink (the data is in json format)
or the incremental field is not set
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/iceberg/src/main/java/org/apache/inlong/sort/iceberg/sink/multiple/IcebergSingleStreamWriter.java