我设置了一个合流的s3接收器连接，它将.avro文件存储在s3中。
我转储了那些文件，发现它们只是消息本身，我不知道在哪里可以找到消息密钥，知道吗？
配置如下：

{
    "name": "s3-sink-test",
    "config": {
        "connector.class": "io.confluent.connect.s3.S3SinkConnector",
        "tasks.max": "1",
        "topics": "book",
        "s3.region": "eu-central-1",
        "s3.bucket.name": "kafka",
        "s3.part.size": "5242880",
        "storage.class": "io.confluent.connect.s3.storage.S3Storage",
        "format.class": "io.confluent.connect.s3.format.avro.AvroFormat",
        "schema.generator.class": "io.confluent.connect.storage.hive.schema.DefaultSchemaGenerator",
        "partitioner.class": "io.confluent.connect.storage.partitioner.TimeBasedPartitioner",
        "path.format": "'year'=YYYY/'month'=MM/'day'=dd/'hour'=HH",
        "locale": "US",
        "timezone": "UTC",
        "partition.duration.ms": "3600000",
        "timestamp.extractor": "RecordField",
        "timestamp.field": "local_timestamp",
        "flush.size": "2",
        "schema.compatibility": "NONE"
    }
}