code: public static boolean isExpression(String token, boolean isXml, JspConfiguration jspConfig, boolean checkDeferred ) {
      	boolean isExpression=JspTranslatorUtil.isExpression(token, isXml);
      	boolean isELInput=JspTranslatorUtil.isELInterpreterInput(token, jspConfig, checkDeferred);
          if (isExpression || isELInput )
              return true;
          else
              return false;
      }
docs: /*
  Checks to see if the given attribute value represents a runtime or EL
  expression.