code: public Element attribute(String attributes)
      {
          if (log.isDebugEnabled() && attributes!=null && attributes.indexOf('=')>=0)
              log.warn("Set attribute with old method: "+attributes+
                           " on " + getClass().getName());
          
          if (attributes==null ||
              this.attributes==null ||
              this.attributes==noAttributes ||
              this.attributes.length()==0)
              this.attributes=attributes;
          else
              this.attributes += ' '+attributes;
          return this;
      }
docs: Add element Attributes.
  The attributes are added to the Element attributes (separated with
  a space). The attributes are available to the derived class in the
  protected member String <I>attributes</I>
  @param attributes String of HTML attributes to add to the element.
  A null attribute clears the current attributes.
  @return This Element so calls can be chained.