code: protected boolean hasNoInvalidScope(Attributes a) {
          String scope = a.getValue(SCOPE);
          if ((scope != null) && !scope.equals(PAGE_SCOPE)
                  && !scope.equals(REQUEST_SCOPE) && !scope.equals(SESSION_SCOPE)
                  && !scope.equals(APPLICATION_SCOPE)) {
              return false;
          }
          return true;
      }
docs: returns true if the 'scope' attribute is valid