@Override
    public boolean equals(Object o) {
        return o instanceof SingleTableCustomFieldsPartitioner;
    }
output: integer list of partitionKeys' corresponding positions within schema
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/kafka/src/main/java/org/apache/inlong/sort/kafka/partitioner/SingleTableCustomFieldsPartitioner.java