title: On Gwt TreeViewModel getNodeInfo() method
body: <p>I can't understand that part, neither trying the showcase examples.</p>
  
  <p>I'm using an extension of AsyncDataProvider to bind my tree to RPC service. Here's my method:</p>
  
  <pre><code>public &lt;T&gt; NodeInfo&lt;?&gt; getNodeInfo(T value) {
          /*
          if (value instanceof Categoria) {
              dataProvider.setCurrentParent((Categoria)value);
          }
          */
          return new DefaultNodeInfo&lt;Categoria&gt;(dataProvider, new CategoriaCell());
      }
  </code></pre>
  
  <p>"currentParent" is my stuff: except for (null => root) values, I set the parent to pass via RPC to my service. Actually, in my widget code:</p>
  
  <pre><code>dataProvider = new CategorieTreeDataProvider() {            
              @Override
              protected void onRangeChanged(HasData&lt;Categoria&gt; display) {
                  updateTree(getCurrentParent());
              }
          };
  
  private void updateTree(Categoria categoria) {
          rpcService.getCategorie(categoria, new AsyncCallback&lt;Categoria[]&gt;() {
              @Override
              public void onSuccess(Categoria[] result) {
                  dataProvider.updateRowCount(result.length, true);
                  dataProvider.updateRowData(0, Arrays.asList(result));
              }
              @Override
              public void onFailure(Throwable caught) {
                  Window.alert(caught.toString());
              }
          });
      }
  </code></pre>
  
  <p>My rpc-server code, however, is working as expected:</p>
  
  <pre><code>@Override
      public Categoria[] getCategorie(Categoria parent) {
          List&lt;Categoria&gt; categoryList = categorieDao.listByProperty("parent", parent);
          for (Categoria c : categoryList) {
              if (categorieDao.listByProperty("parent", c).size() == 0) {
                  c.setLeaf(true);
              }
          }
          return categoryList.toArray(new Categoria[0]);
      }
  </code></pre>
  
  <p>**Then I add some data to my Categories: 'GrandFather', 'Father' and 'Son'.</p>
  
  <p>Unfortunately, after loading my widget, I see:</p>
  
  <ul>
  <li><p>The grandfather correctly, with his "+" how expected;</p></li>
  <li><p>Then I click it and... </p></li>
  <li><p>The grandfather disappear and I see 'Father' with his '+' </p></li>
  <li><p>same for father -> son</p></li>
  </ul>
  
  <p>I suspect the bug is in updateRowCount / updateRowData usage.**</p>
  
  <p>Any ideas?</p>