private Collection<Classification> getChildren(
     Classification nodo, Collection<Classification> lista) {
   for (Classification classif : lista) {
     if (nodo.getClassificationCod() != null
         && classif.getClassificationCod() != null
         && nodo.getClassificationCod().equals(classif.getClassificationCod())) {
       return classif.getClassificationList();
     }
   }
   return null;
 }
  private TreeNode createTree(Classification raiz, Collection<Classification> lista) {
    TreeNode node = new DefaultTreeNode(raiz, null);
    TreeNode child = null;

    Collection<Classification> hijos = getChildren(raiz, lista);

    for (Classification hijo : hijos) {
      if (hijo.getClassificationList() != null) {
        child = createTree(hijo, lista);
        child.setParent(node);
      } else {
        child = new DefaultTreeNode(hijo, node);
        child.setParent(node);
      }
      // node.addChild(child);

    }
    return node;
  }