public Builder equalityFieldColumns(List<String> columns) {
            this.equalityFieldColumns = columns;
            return this;
        }
Configuring the equality field columns for iceberg table that accept CDC or UPSERT events.

@param columns defines the iceberg table's key.
@return {@link Builder} to connect the iceberg table.
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/iceberg/src/main/java/org/apache/inlong/sort/iceberg/sink/FlinkSink.java