Convert, ConvertLists in one ConvertAll

This code is able to perform a global convert on pojo or struts form.
 Also, it keeps the original state of the object pass through the method.
 (convertLists change the original object and i think it's boring)
 
 
 public static Object convertAll(Object o) throws Exception {
         if (o == null) {
             return null;
         }
         Object targetO = getOpposingObject(o);
         BeanUtils.copyProperties(targetO, o);
 
         Object target = null;
 
         PropertyDescriptor[] origDescriptors =
                 PropertyUtils.getPropertyDescriptors(o);
 
         for (int i = 0; i < origDescriptors.length; i++) {
             String name = origDescriptors[i].getName();
 
             if (origDescriptors[i].getPropertyType().equals(List.class)) {
                 List list = (List) PropertyUtils.getProperty(o, name);
                 List b =null;
                 if(list!=null)
                     b = new ArrayList(list.size());
 
                 for (int j=0; j < list.size(); j++) {
                     Object origin = list.get(j);
                     // je convertit l'objet dans la liste
                     target = convert(origin);
 
                     b.add(target);
                 }
                 PropertyUtils.setProperty(targetO, name, b);
             }
         }
         return targetO;
    }

and add to the BaseAction class the method convertAll