code: private void performObservation(PhaseEvent event, PhaseIdType phaseIdType) {
          UIViewRoot viewRoot = (UIViewRoot) event.getFacesContext().getViewRoot();
          List<? extends Annotation> restrictionsForPhase = getRestrictionsForPhase(phaseIdType, viewRoot.getViewId());
          if (restrictionsForPhase != null) {
              log.debugf("Enforcing on phase %s", phaseIdType);
              enforce(event.getFacesContext(), viewRoot, restrictionsForPhase);
          }
      }
docs: Inspect the annotations in the ViewConfigStore, enforcing any restrictions applicable to this phase
  
  @param event
  @param phaseIdType