title: Kafka Connect topic.key.ignore not works as expected
body: <p>As I understand from the documentation of kafka connect this configuration should ignore the keys for metricbeat and filebeat topic but not for alarms. But kafka connect does not ignore any key. </p>
  
  <p>So that's the fully json config that i pushing to kafka-connect over rest</p>
  
  <pre><code>{
   "auto.create.indices.at.start": false,
   "connector.class": "io.confluent.connect.elasticsearch.ElasticsearchSinkConnector",
   "connection.url": "http://elasticsearch:9200",
   "connection.timeout.ms": 5000,
   "read.timeout.ms": 5000,
   "tasks.max": "5",
   "topics": "filebeat,metricbeat,alarms",
   "behavior.on.null.values": "delete",
   "behavior.on.malformed.documents": "warn",
   "flush.timeout.ms":60000,
   "max.retries":42,
   "retry.backoff.ms": 100,
   "max.in.flight.requests": 5,
   "max.buffered.records":20000,
   "batch.size":4096,
   "drop.invalid.message": true,
   "schema.ignore": true,
   "topic.key.ignore": "metricbeat,filebeat",
   "key.ignore": false
   "name": "elasticsearch-ecs-connector",
   "type.name": "_doc",
   "value.converter": "org.apache.kafka.connect.json.JsonConverter",
   "value.converter.schemas.enable": "false",
   "transforms":"routeTS",
   "transforms.routeTS.type":"org.apache.kafka.connect.transforms.TimestampRouter",
   "transforms.routeTS.topic.format":"${topic}-${timestamp}",
   "transforms.routeTS.timestamp.format":"YYYY.MM.dd",
   "errors.tolerance": "all" ,
   "errors.log.enable": false ,
   "errors.log.include.messages": false,
   "errors.deadletterqueue.topic.name":"logstream-dlq",
   "errors.deadletterqueue.context.headers.enable":true ,
   "errors.deadletterqueue.topic.replication.factor": 1
  }
  </code></pre>
  
  <p>That's the logging during start of the connector </p>
  
  <pre><code>[2020-05-01 21:07:49,960] INFO ElasticsearchSinkConnectorConfig values:
      auto.create.indices.at.start = false
      batch.size = 4096
      behavior.on.malformed.documents = warn
      behavior.on.null.values = delete
      compact.map.entries = true
      connection.compression = false
      connection.password = null
      connection.timeout.ms = 5000
      connection.url = [http://elasticsearch:9200]
      connection.username = null
      drop.invalid.message = true
      elastic.https.ssl.cipher.suites = null
      elastic.https.ssl.enabled.protocols = [TLSv1.2, TLSv1.1, TLSv1]
      elastic.https.ssl.endpoint.identification.algorithm = https
      elastic.https.ssl.key.password = null
      elastic.https.ssl.keymanager.algorithm = SunX509
      elastic.https.ssl.keystore.location = null
      elastic.https.ssl.keystore.password = null
      elastic.https.ssl.keystore.type = JKS
      elastic.https.ssl.protocol = TLS
      elastic.https.ssl.provider = null
      elastic.https.ssl.secure.random.implementation = null
      elastic.https.ssl.trustmanager.algorithm = PKIX
      elastic.https.ssl.truststore.location = null
      elastic.https.ssl.truststore.password = null
      elastic.https.ssl.truststore.type = JKS
      elastic.security.protocol = PLAINTEXT
      flush.timeout.ms = 60000
      key.ignore = false
      linger.ms = 1
      max.buffered.records = 20000
      max.in.flight.requests = 5
      max.retries = 42
      read.timeout.ms = 5000
      retry.backoff.ms = 100
      schema.ignore = true
      topic.index.map = []
      topic.key.ignore = [metricbeat, filebeat]
      topic.schema.ignore = []
      type.name = _doc
      write.method = insert
  </code></pre>
  
  <p>Iam using Confluent Platform 5.5.0</p>