title: MapStruct bulk conversion with @aftermapping
body: <p>I want to apply a decoration using a dedicated @AfterMapping after the single item conversion of a DTO and another dedicated @AfterMapping when dealing with its collection conversion flavor but not both. </p>
  
  <pre><code>public abstract CatUI convert(Cat cat);
  public abstract List&lt;CatUI&gt; convert(List&lt;Cat&gt; cats);
  
  
  @AfterMapping
  public void populateCatName(Cat cat, @MappingTarget CatUI catUI) {
       String name = _someRemoteService.getCatName(catUI.getId());
       catUI.setName(name);
  }
  
  @AfterMapping
  public void populateCatNames(List&lt;Cat&gt; cats, @MappingTarget List&lt;CatUI&gt; catUIs) {
       Map&lt;Integer,String&gt; idToNameMap = _someRemoteService.getCatNames(catUIs.stream().map((c) -&gt; c.getId() ).collect(Collectors.toList());
       catUIs.forEach((c) -&gt; c.setName(idToNameMap(c.getId())));
  }
  </code></pre>
  
  <p>I don't want populateCatName to be called when dealing with List conversion and hence duplicate my decoration.</p>
  
  <p>Anyway to do this?</p>