code: public static Throwable getThrowable(ServletRequest req) {
  
          CmsFlexController controller = (CmsFlexController)req.getAttribute(ATTRIBUTE_NAME);
          if (controller != null) {
              return controller.getThrowable();
          } else {
              return null;
          }
      }
docs: Provides access to a root cause Exception that might have occurred in a complex include scenario.<p>
  
  @param req the current request
  
  @return the root cause exception or null if no root cause exception is available
  
  @see #getThrowable()