docs: public void setAttribute(String attributeName, Object value) {
          synchronized (_iSession) {
              if (!_iSession.isValid())
                  throw new IllegalStateException();
              if (null != value) {
                  if (!(value instanceof HttpSessionBindingListener)) {
                      _iSession.setAttribute(attributeName, value, Boolean.FALSE);
                  } else {
                      _iSession.setAttribute(attributeName, value, Boolean.TRUE);
                  }
              }
          }
      }