title: Kafka-connect issue
body: <p>I installed Apache Kafka on centos 7 (confluent), am trying to run filestream kafka connect in distributed mode but I was getting below error:</p>
  
  <pre><code>[2017-08-10 05:26:27,355] INFO Added alias 'ValueToKey' to plugin 'org.apache.kafka.connect.transforms.ValueToKey' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader:290)
  Exception in thread "main" org.apache.kafka.common.config.ConfigException: Missing required configuration "internal.key.converter" which has no default value.
  at org.apache.kafka.common.config.ConfigDef.parseValue(ConfigDef.java:463)
  at org.apache.kafka.common.config.ConfigDef.parse(ConfigDef.java:453)
  at org.apache.kafka.common.config.AbstractConfig.&lt;init&gt;(AbstractConfig.java:62)
  at org.apache.kafka.common.config.AbstractConfig.&lt;init&gt;(AbstractConfig.java:75)
  at org.apache.kafka.connect.runtime.WorkerConfig.&lt;init&gt;(WorkerConfig.java:197)
  at org.apache.kafka.connect.runtime.distributed.DistributedConfig.&lt;init&gt;(DistributedConfig.java:289)
  at org.apache.kafka.connect.cli.ConnectDistributed.main(ConnectDistributed.java:65)
  </code></pre>
  
  <p>Which is now resolved by updating the workers.properties as mentioned in <a href="http://docs.confluent.io/current/connect/userguide.html#connect-userguide-distributed-config" rel="nofollow noreferrer">http://docs.confluent.io/current/connect/userguide.html#connect-userguide-distributed-config</a></p>
  
  <p><code>Command used:</code></p>
  
  <pre><code>/home/arun/kafka/confluent-3.3.0/bin/connect-distributed.sh ../../../properties/file-stream-demo-distributed.properties
  </code></pre>
  
  <p><code>Filestream properties file (workers.properties):</code></p>
  
  <pre><code>name=file-stream-demo-distributed
  connector.class=org.apache.kafka.connect.file.FileStreamSourceConnector
  tasks.max=1
  file=/tmp/demo-file.txt
  bootstrap.servers=localhost:9092,localhost:9093,localhost:9094
  config.storage.topic=demo-2-distributed
  offset.storage.topic=demo-2-distributed
  status.storage.topic=demo-2-distributed
  key.converter=org.apache.kafka.connect.json.JsonConverter
  key.converter.schemas.enable=true
  value.converter=org.apache.kafka.connect.json.JsonConverter
  value.converter.schemas.enable=true
  internal.key.converter=org.apache.kafka.connect.json.JsonConverter
  internal.key.converter.schemas.enable=false
  internal.value.converter=org.apache.kafka.connect.json.JsonConverter
  internal.value.converter.schemas.enable=false
  group.id=""
  </code></pre>
  
  <p>I added below properties and command went through without any errors.</p>
  
  <pre><code>bootstrap.servers=localhost:9092,localhost:9093,localhost:9094
  config.storage.topic=demo-2-distributed
  offset.storage.topic=demo-2-distributed
  status.storage.topic=demo-2-distributed
  group.id=""
  </code></pre>
  
  <p>But, now when I run consumer command, I am unable to see the messages in /tmp/demo-file.txt. Please let me know if there is a way I can check if the messages are published to kafka topics and partitions ?</p>
  
  <pre><code>kafka-console-consumer --zookeeper localhost:2181 --topic demo-2-distributed --from-beginning
  </code></pre>
  
  <p>I believe I am missing something really basic here. Can some one please help?</p>