title: Is there a way to use method 'orElseGet' of 'Optional' to create a new list when it is null?
body: <p>Say we have a class in the structure as below:</p>
  
  <pre><code>class Resource{
     String id; 
     String name;
     List&lt;String&gt; friends;
  }
  </code></pre>
  
  <p>Is there a way to get the list using 'Optional' in this way:</p>
  
  <pre><code>Optional.of(resource.getFriends()).map(friends -&gt; {
      friends.add("John");
      return friends;
  }).orElseGet(
      //do something here.
  )
  </code></pre>
  
  <p>A new list is expected if there was no one before.</p>