Java Apache Kafka的自定义主题路由'；s mongoSourceConnector

我正在使用ApacheKafka和MongoSourceConnect来接收数据库更改，例如文档插入，并希望将其发送给Kafka。在我的文档字段中，我将发送一个主题键，该键将把默认卡夫卡主题重写为文档的字段主题值

为此，我尝试了smt ExtractTopic$值（io.confluent.connect.transforms.ExtractTopic）

我的配置如下所示：

name=mongo-source
connector.class=com.mongodb.kafka.connect.MongoSourceConnector
tasks.max=1

# Connection and source configuration
connection.uri=<my_connection_uri>
database=<my_db>
collection=messages

#topic.prefix=
poll.max.batch.size=1000
poll.await.time.ms=5000

# Change stream options
pipeline=[{"$match": { "$or": [{"operationType": "insert"},{"operationType": "update"}]}}]
batch.size=0
change.stream.full.document=updateLookup
publish.full.document.only=true
collation=

key.converter=org.apache.kafka.connect.storage.StringConverter
value.converter=org.apache.kafka.connect.storage.StringConverter

key.converter.schemas.enable=true
value.converter.schemas.enable=true

# key.converter=org.apache.kafka.connect.json.JsonConverter
# value.converter=org.apache.kafka.connect.json.JsonConverter

transforms=ValueFieldExample
transforms.ValueFieldExample.type=io.confluent.connect.transforms.ExtractTopic$Value
transforms.ValueFieldExample.field=topic

但如果正在使用smt转换（ExtractTopic），则抛出：

Caused by: org.apache.kafka.connect.errors.DataException: Only Struct objects supported for [field extraction], found: java.lang.String

Caused by: org.apache.kafka.connect.errors.DataException: Only Struct objects supported for [field extraction], found: java.lang.String