title: mapstruct map iterable to non iterable
body: <p>I want to map a list of Objects to an Object that contains a list:</p>
  
  <pre><code>public class Group {
      private List&lt;Person&gt; people;
  }
  
  public class Person {
      private String name;
  }
  </code></pre>
  
  <p>I tried creating a mapper like this:</p>
  
  <pre><code>Group toGroup(List&lt;Person&gt; people);
  </code></pre>
  
  <p>and I'm getting this error:</p>
  
  <pre><code>error: Can't generate mapping method from iterable type to non-iterable type.
  </code></pre>
  
  <p>What is the most elegant solution for this kind of mapping?</p>