title: How to set default value and also use Environment variable in application.conf
body: <p><br/>
  I want to set value for one of config variable in application.conf using environment variable. But if this env variable is not present I want to default config to a certain value instead of erring out. <br/>
  Is this possible? Here is setting for reference. <br/></p>
  
  <pre><code>test.myframework {
  host = ${TEST_HOST_NAME}
  }
  </code></pre>
  
  <p>Here if TEST_HOST_NAME if not present can I default host to localhost?</p>