title: Kafka Connect SMT to add Kafka header fields
body: <p>I need to find or write an SMT that will add header fields to a request.  The request is missing some type fields and I want to add them.</p>
  <p>How exactly do you add a header within an SMT all I have seen are just record transforms like below but what if its the header I want to change or add a field to?</p>
  <pre><code>   private R applySchemaless(R record) {
  
     final Map&lt;String, Object&gt; value = requireMap(operatingValue(record), PURPOSE);
    // record.headers.add(Header)  but how do I define the header
    // or record.headers.add(String, Schema) but I am not sure how to define Schema? 
    final Map&lt;String, Object&gt; updatedValue = new HashMap&lt;&gt;(value);
  
    updatedValue.put(fieldName, getRandomUuid());
    
  
    return newRecord(record, null, updatedValue);
    
  }
  </code></pre>