docs: @InternalFunction()
      public Boolean unique(final List<ProxyField> list)
      {
      	if (list == null)
      	{
      		return Boolean.TRUE;
      	}
          int size = list.size();
          int index = 0;
          for (ProxyField proxyField: list)
          {
              for (int i=index+1;i<size;i++)
              {
                  if (list.get(i).getValue().equals(proxyField.getValue()))
                  {
                      return Boolean.FALSE;
                  }
              }
          }
          return Boolean.TRUE;
      }