presto-kafka/src/main/java/io/prestosql/plugin/kafka/KafkaHandleResolver.java/KafkaHandleResolver/convertSplit
class KafkaHandleResolver:    static KafkaSplit convertSplit(ConnectorSplit split)
    {
        requireNonNull(split, "split is null");
        checkArgument(split instanceof KafkaSplit, "split is not an instance of KafkaSplit");
        return (KafkaSplit) split;
    }