title: Schema exception on Kafka jdbc sink connect
body: <p>I am trying to insert rows into my Oracle table using Kafka jdbc sink connect. I have messages in my Kafka topic (JSON) like below; </p>
  
  <pre><code>[{"f1":"qws","f2":"zcz","f3":"SDFF","f4":"f33bfed577bcd7c4625479bd3cd13323--1132061303","f5":null,"f6":null,"f7":"ghSDAgh/akdjytfd/jhsgd","f8":"hsfgd/sdfjghsfjd/jsg","f9":null,"f10":"ASD","f11":"sdfg/vbnm","f12":"S","startTime":"2018-01-30T05:24:41.162","_startTime":"DATE","f13":219,"f14":"http://192.168.0.1:1234/asd/fgh/jkl/zxc/vbn/qwe/rty","f15":"fe80:0:0:0:7501:14d9:b44b:2a95%eth5","f16":1234,"f17":"ABCD-1234","f18":"192.168.0.1","f19":"sdfgd","dfgVO":{"fa1":null,"fa2":"formats","fa3":""qwe.rty.uiop.asd.fgh.jkl.zxc.vbn.asdf@61e97f29"","fa4":7,"fa5":79,"fa6":null,"fa7":"{}","fa8":1517289881381},"f20":null,"f21":"http-drte-1234-uik-7","f22":false,"f23":false,"f24":false}]
  </code></pre>
  
  <p>I have the connector configuration like below; </p>
  
  <pre><code>name=jdbc-sink-2
  connector.class=io.confluent.connect.jdbc.JdbcSinkConnector
  tasks.max=1
  topics=my_topic_1
  connection.url=jdbc:oracle:thin:@192.168.0.1:1521:user01
  connection.user=USER1
  connection.password=PASSWD1
  auto.create=true
  table.name.format=MY_TABLE_2
  key.converter=org.apache.kafka.connect.json.JsonConverter
  value.converter=org.apache.kafka.connect.json.JsonConverter
  producer.retries=1
  </code></pre>
  
  <p>When I start the connector, I am getting the error below; </p>
  
  <pre><code>[2018-01-30 11:16:55,417] ERROR Task jdbc-sink-2 threw an uncaught and unrecoverable exception (org.apache.kafka.connect.runtime.WorkerTask:148)
  org.apache.kafka.connect.errors.DataException: JsonConverter with schemas.enable requires "schema" and "payload" fields and may not contain additional fields. If you are trying to deserialize plain JSON data, set schemas.enable=false in your converter configuration.
  at org.apache.kafka.connect.json.JsonConverter.toConnectData(JsonConverter.java:308)
  at org.apache.kafka.connect.runtime.WorkerSinkTask.convertMessages(WorkerSinkTask.java:406)
  at org.apache.kafka.connect.runtime.WorkerSinkTask.poll(WorkerSinkTask.java:250)
  at org.apache.kafka.connect.runtime.WorkerSinkTask.iteration(WorkerSinkTask.java:180)
  at org.apache.kafka.connect.runtime.WorkerSinkTask.execute(WorkerSinkTask.java:148)
  at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:146)
  at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:190)
  at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
  at java.util.concurrent.FutureTask.run(FutureTask.java:266)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
  at java.lang.Thread.run(Thread.java:745)
  [2018-01-30 11:16:55,422] ERROR Task is being killed and will not recover until manually restarted (org.apache.kafka.connect.runtime.WorkerTask:149)
  </code></pre>
  
  <p>Then I added the below configurations to my existing connector configuration; </p>
  
  <pre><code>key.converter.schemas.enable=false
  value.converter.schemas.enable=false
  </code></pre>
  
  <p>Now, I am getting another error like below; </p>
  
  <pre><code>[2018-01-30 11:36:58,118] ERROR Task jdbc-sink-2 threw an uncaught and unrecoverable exception (org.apache.kafka.connect.runtime.WorkerSinkTask:455)
  org.apache.kafka.connect.errors.ConnectException: No fields found using key and value schemas for table: MY_TABLE_2
  at io.confluent.connect.jdbc.sink.metadata.FieldsMetadata.extract(FieldsMetadata.java:190)
  at io.confluent.connect.jdbc.sink.metadata.FieldsMetadata.extract(FieldsMetadata.java:58)
  at io.confluent.connect.jdbc.sink.BufferedRecords.add(BufferedRecords.java:65)
  at io.confluent.connect.jdbc.sink.JdbcDbWriter.write(JdbcDbWriter.java:62)
  at io.confluent.connect.jdbc.sink.JdbcSinkTask.put(JdbcSinkTask.java:66)
  at org.apache.kafka.connect.runtime.WorkerSinkTask.deliverMessages(WorkerSinkTask.java:435)
  at org.apache.kafka.connect.runtime.WorkerSinkTask.poll(WorkerSinkTask.java:251)
  at org.apache.kafka.connect.runtime.WorkerSinkTask.iteration(WorkerSinkTask.java:180)
  at org.apache.kafka.connect.runtime.WorkerSinkTask.execute(WorkerSinkTask.java:148)
  at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:146)
  at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:190)
  at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
  at java.util.concurrent.FutureTask.run(FutureTask.java:266)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
  at java.lang.Thread.run(Thread.java:745)
  [2018-01-30 11:36:58,123] ERROR Task is being killed and will not recover until manually restarted (org.apache.kafka.connect.runtime.WorkerSinkTask:456)
  [2018-01-30 11:36:58,124] ERROR Task jdbc-sink-2 threw an uncaught and unrecoverable exception (org.apache.kafka.connect.runtime.WorkerTask:148)
  org.apache.kafka.connect.errors.ConnectException: Exiting WorkerSinkTask due to unrecoverable exception.
  at org.apache.kafka.connect.runtime.WorkerSinkTask.deliverMessages(WorkerSinkTask.java:457)
  at org.apache.kafka.connect.runtime.WorkerSinkTask.poll(WorkerSinkTask.java:251)
  at org.apache.kafka.connect.runtime.WorkerSinkTask.iteration(WorkerSinkTask.java:180)
  at org.apache.kafka.connect.runtime.WorkerSinkTask.execute(WorkerSinkTask.java:148)
  at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:146)
  at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:190)
  at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
  at java.util.concurrent.FutureTask.run(FutureTask.java:266)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
  at java.lang.Thread.run(Thread.java:745)
  [2018-01-30 11:36:58,125] ERROR Task is being killed and will not recover until manually restarted (org.apache.kafka.connect.runtime.WorkerTask:149)
  </code></pre>
  
  <p>This says that I need to modify my Kafka message like key value schema format. I cannot modify my Kafka message format since it is published by someone else. How can I fix this error? </p>
  
  <p>Thank you. </p>