请问 Confluent HDFS Connector中format.class的类型还有哪些呢？在confluent文档里没有找到

https://docs.confluent.io/current/connect/connect-hdfs/docs/configuration_options.html#hdfs

format.class
The format class to use when writing data to HDFS.

Type: string
Default: io.confluent.connect.hdfs.avro.AvroFormat
Importance: high

默认存入为.avro格式，请问如何配置使存入HDFS的文件为.txt