title: How to specify classes output directory for Gradle 4?
body: <p>Gradle project deprecated 'classesDir' so the previously working method:</p>
  
  <pre><code>sourceSets {
      main {
          output.classesDir = "myDir"
      }
  }
  </code></pre>
  
  <p>should be replaced with something else. Documentation talks about 'output.classesDirs' but this is read-only property. </p>
  
  <p>What is the method to specify <strong>custom compilation output directory</strong> in Gradle 4.x scripts?</p>