code: public static String evalString(String propertyName, String propertyValue, Tag tag, PageContext pageContext) throws JspException{
      	
      	return (String) ExpressionEvaluatorManager.evaluate(propertyName,
      			propertyValue, String.class, tag, pageContext);
      }
docs: Evaluate the string EL expression passed as parameter
  @param propertyName the property name
  @param propertyValue the property value
  @param tag the tag
  @param pageContext the page context
  @return the value corresponding to the EL expression passed as parameter
  @throws JspException if an exception occurs