title: mapstruct - Propagate parent field value to collection of nested objects
body: <p>Is it possible to propagate value form a parent object to collection of nested objects? For example</p>
  
  <p><strong><em>Source DTO classes</em></strong></p>
  
  <pre><code>class CarDTO {
    private String name;
    private long userId;
    private Set&lt;WheelDto&gt; wheels; 
  };
  
  class WheelDto {
    private String name;
  }
  </code></pre>
  
  <p><strong><em>Target entity classes</em></strong></p>
  
  <pre><code>class Car {
    private String name;
    private long userId;
    private Set&lt;Wheel&gt; wheels; 
  };
  
  class Wheel {
    private String name;
    private long lastUserId;
  }
  </code></pre>
  
  <p>As you could see I do not have lastUserId on WheelDto, hence I would like to map userId from CarDto to lastUserId on WheelDto on each object in a wheels collection
  I tried  </p>
  
  <pre><code>@Mapping(target = "wheels.lastUserId", source = "userId") 
  </code></pre>
  
  <p>but no luck</p>