code: public void addParameter(String name, Object value, String facet)
              throws JspException
      {
          assert(name != null) : "Parameter 'name' must not be null";
  
          if (_params == null) {
              _params = new HashMap();
          }
          ParamHelper.addParam(_params, name, value);
      }
docs: Adds a URL parameter to the generated hyperlink.
  @param name  the name of the parameter to be added.
  @param value the value of the parameter to be added (a String or String[]).
  @param facet