code: @MapMethod
      public List<Map<String,Object>> diff(Map<String,Object> old, Map<String,Object> nw){
          List<ObjectDiff.DiffBean> l = Objects.diff(old,nw);
          List<Map<String,Object>> list = Objects.newArrayList();
          for(ObjectDiff.DiffBean b:l){
              list.add(Objects.newHashMap(String.class,Object.class,
                      "path",b.getPath(),"old",b.getOldValue(),"new",b.getNewValue()
              ));
          }
          return list;
      }
docs: @see org.s1.objects.Objects#diff(java.util.Map, java.util.Map)
  
  @param old
  @param nw
  @return