title: Configure ModelMapper to map nested object to field
body: <p>Here are my DTOs:</p>
  
  <pre><code>public class TagVolumeDTO {
      private Long id;
      private Long idTag;
      //...
  }
  
  public class TagTDO {
      private Long id;
      private Long amount;
      //...
  }
  </code></pre>
  
  <p>and here are my entities:</p>
  
  <pre><code>public class TagVolume {
      private Long id;
      private Tag tag;
      //...
  }
  
  public class Tag {
      private Long id;
      private Long amount;
      //...
  }
  </code></pre>
  
  <p>I would like to configure my ModelMapper to map Tag#id to TagVolumeDTO#idTag.
  Is that possible?</p>