title: How does kafka and schema registry share KafkaProperties? ('basic.auth.user.info' was supplied but isn't a known config.)
body: <p>I still cannot wrap my head around how is kafka producers / consumers <em>and</em> schema registry intended to reuse <code>KafkaProperties</code>. Or is it not intended to reuse same structures?</p>
  <p>so for schema registry, I have to configure for example following properties:</p>
  <ul>
  <li>spring.kafka.basic.auth.credentials.source</li>
  <li>spring.kafka.basic.auth.user.info</li>
  <li>spring.kafka.producer.properties.schema.registry.url</li>
  <li>spring.kafka.consumer.properties.schema.registry.url</li>
  </ul>
  <p>but if I do so, and call <code>org.springframework.boot.autoconfigure.kafka.KafkaProperties#buildConsumerProperties</code></p>
  <p>and proceed with build hashmap I will get for example warning:</p>
  <p><code>The configuration 'schema.registry.url' was supplied but isn't a known config.</code></p>
  <p>I saw recommendation to set schema registry urls as such, I also saw setting <code>basic.auth…</code> like this. I really cannot get it working. I mean the app is working, I just get several pages of these warnings. I'd like to know how to configure the app correctly, as it was intended by design, so that I can share 1 configuration for confluent kafka and schema-registry configuration</p>
  <p>Sure I can get separate configuration of properties &quot;to be added&quot; for schema registry, or bend it somehow, so that I can build separate set of properties for both, but it just don't feel right, this clearly isn't how it was (I hope) designed. What is the correct procedure here? Maybe it's hidden somewhere in depth of autoconfiguration, but if its there I cannot find it.</p>