title: Kafka Connect HDFS Sink for JSON format using JsonConverter
body: <p>Produce to/Consume from Kafka in JSON. Save to HDFS in JSON using below properties :</p>
  
  <pre><code>key.converter=org.apache.kafka.connect.json.JsonConverter
  value.converter=org.apache.kafka.connect.json.JsonConverter
  key.converter.schemas.enable=false
  value.converter.schemas.enable=false
  </code></pre>
  
  <p>Producer :</p>
  
  <pre><code>curl -X POST -H "Content-Type: application/vnd.kafka.json.v1+json" \
        --data '{"schema": {"type": "boolean", "optional": false, "name": "bool", "version": 2, "doc": "the documentation", "parameters": {"foo": "bar" }}, "payload": true }' "http://localhost:8082/topics/test_hdfs_json"
  </code></pre>
  
  <p>Consumer :</p>
  
  <pre><code>./bin/connect-standalone etc/schema-registry/connect-avro-standalone.properties etc/kafka-connect-hdfs/quickstart-hdfs.properties
  </code></pre>
  
  <p>Issue-1:</p>
  
  <pre><code>key.converter.schemas.enable=true
  
  value.converter.schemas.enable=true
  </code></pre>
  
  <p>Getting Exception:</p>
  
  <pre><code>org.apache.kafka.connect.errors.DataException: JsonDeserializer with schemas.enable requires "schema" and "payload" fields and may not contain additional fields
      at org.apache.kafka.connect.json.JsonConverter.toConnectData(JsonConverter.java:332)
  </code></pre>
  
  <p>Issue-2:</p>
  
  <p>Enabling above two properties is not throwing any issue, but no data are written over hdfs.</p>
  
  <p>Any suggestion will be highly appreciated.</p>
  
  <p>Thanks</p>