code: private ExpressionEvaluator getExpressionEvaluator()
      {
          if (ee == null)
              ee = ExpressionEvaluatorFactory.getInstance();
  
          assert(ee != null);
          return ee;
      }
docs: Return a cached instance of an <code>ExpressionEvaluator</code>.  This will be cached by the
  tag and release during <code>localRelease</code>.
  @return the <code>ExpressionEvalutor</code> for tis tag.