@Override
    public SourceReader<OUT, KafkaPartitionSplit> createReader(SourceReaderContext readerContext)
            throws Exception {
        return createReader(readerContext, (ignore) -> {
        });
    }
Get a kafkaSourceBuilder to build a {@link KafkaSource}.

@return a Kafka source builder.
inlong-sort/sort-flink/sort-flink-v1.18/sort-connectors/kafka/src/main/java/org/apache/inlong/sort/kafka/source/KafkaSource.java