When using ExtJsonConverter with Apicurio service I get NullPointerExceptions. There is probably a mistake in the configuration, but I can't figure out how to configure serializer and converter to cooperate. 

I am using following properties for the connector: 
connector.class=org.apache.camel.kafkaconnector.elasticsearchrest.CamelElasticsearchrestSinkConnector
camel.sink.endpoint.operation=Index
value.converter.apicurio.registry.url=localhost:49161/api
value.converter.apicurio.registry.global-id=io.apicurio.registry.utils.serde.strategy.GetOrCreateIdStrategy
tasks.max=1
topics=JsonSchemaTestTopic
value.converter.apicurio.registry.use.headers=true
camel.sink.endpoint.hostAddresses=localhost:49155
camel.sink.path.clusterName=docker-cluster
camel.sink.endpoint.indexName=ckc-index
name=CamelElasticSearchSinkConnector
value.converter=io.apicurio.registry.utils.converter.ExtJsonConverter
key.converter=org.apache.kafka.connect.storage.StringConverter
And the producer producing messages is configured use the same apicurio registry and stores the artifact id in headers. 
Is there any additional config needed to tell the converter to use headers for the artifact id? 
In the opposite case if I want to have the schema in the message body what do I need to configure?