code: public String transformToString() {
          StringWriter sw = new StringWriter();
          transformTo(new StreamResult(sw));
          return sw.toString();
      }
docs: Convenience method that returns the result of the
  transformation as a String.
  
  @exception IllegalArgumentException if source is null
  @exception ConfigurationException if the TraX system isn't
  configured properly
  @exception XMLUnitException if the transformation throws an
  exception