title: How to add new sourceset with gradle kotlin-dsl
body: <p>I want to add a sourceset <code>src/gen/java</code>. With groovy this is rather easy and already described in <a href="https://discuss.gradle.org/t/how-to-use-gradle-with-generated-sources/9401/5" rel="noreferrer">https://discuss.gradle.org/t/how-to-use-gradle-with-generated-sources/9401/5</a></p>
  
  <pre><code>sourceSets {
     gen {
          java.srcDir "src/gen/java"
      }
  }
  </code></pre>
  
  <p>But I stuck with the kotlin-dsl to add a new one. All I've got is:</p>
  
  <pre><code>java {
      sourceSets {
  
      }
  }
  </code></pre>
  
  <p>Can anyone help here to </p>