The URLTag has a property 'includeParams' that specifies whether the generated url will contain the parameters of the current reqeust. This feature cannot be used unless no 'value' attribute is specified (value != null).

My application uses the 'includeParams' property to pass state from page to page instead of using a session.

My change was to just comment out the lines:

if (value == null) {
   ...
  }