code: public Kafka sinkPartitionerCustom(Class<? extends FlinkKafkaPartitioner> partitionerClass) {
  		sinkPartitionerType = CONNECTOR_SINK_PARTITIONER_VALUE_CUSTOM;
  		sinkPartitionerClass = Preconditions.checkNotNull(partitionerClass);
  		return this;
  	}
docs: Configures how to partition records from Flink's partitions into Kafka's partitions.
  
  <p>This strategy allows for a custom partitioner by providing an implementation
  of {@link FlinkKafkaPartitioner}.