title: How reuse properties in typesafe config files?
body: <p>Consider following files:</p>
  
  <p><strong>application.conf</strong></p>
  
  <pre><code>app {
      port = 5000
  }
  </code></pre>
  
  <p><strong>reference.conf</strong></p>
  
  <pre><code>akka {
      cluster {
          seed-nodes = ["akka.tcp://sysName@localhost:"${app.port}]
      }
  }
  </code></pre>
  
  <p>So when I run <code>ConfigFactory.load()</code> it fails, because <code>${app.port}</code> does not present in reference.conf.</p>
  
  <p>But load algorithm is clear - <code>reference.conf</code> is loaded and merged with <code>application.conf</code>. Is there a way to load <code>application.conf</code> and "include" <code>reference.conf</code> into it?</p>
  
  <p><strong>IMPORTANT</strong></p>
  
  <p>I tried add <code>include "reference.conf"</code> at the first line in <code>application.conf</code> it does not help.</p>