title: How to serialize an AVRO schema-compliant JSON message?
body: <p>Given an AVRO schema, I create a JSON string which conforms to this schema.
  How can I serialize the <em>JSON string</em> using AVRO to pass it to a Kafka producer which expects an AVRO-encoded message?</p>
  <p>All examples I find don't have JSON as input.</p>
  <p>BTW, the receiver will then deserialize the message to a POJO - we are working in different tech stacks. So, basically it's JSON -&gt; Kafka -&gt; POJO.</p>