Send AVRO content to kafka

Hi,

We try to send kafka message using AVRO and schema registry.

Right now, we've been trying to do something like this:

on configuration
``` properties
key.serializer=org.apache.kafka.common.serialization.StringSerializer
value.serializer=io.confluent.kafka.serializers.KafkaAvroSerializer
```

on test

``` json
{
"name":"send avro message",
"url":"kafka-topic:command",
"operation":"produce",
"request": {
"recordType" : "JSON",
"records": [
{
"key": "test",
"value": {
"property" : "001"
}
}
]
},
"verify": {
"status": "Ok",
"recordMetadata": "$NOT.NULL"
}
}
```

ZeroCode serialize this code using avro and send it. But it doesn't use the existing schema for the object.
On the schema registry, we have this schema:
``` json
{
"type" : "record",
"name" : "TestKafkaMessage",
"namespace" : "com.foo.bar",
"fields" : [ {
"name" : "property",
"type" : "string"
}]
}
```

Instead of use the existing schema, it create a new one `command-value` with the content :

``` json
"string"
```

#### Expected Behaviour:

Be able to specify a schema (using file, json, or schema registry reference) to serialize json using this schema.

Is this already possible? Is there any other way?

Thanks