code: @Override
      public void processPartial(PhaseId phaseId)
      {
          assertNotReleased();
  
          UIViewRoot viewRoot = _facesContext.getViewRoot();
  
          if (phaseId == PhaseId.APPLY_REQUEST_VALUES
                  || phaseId == PhaseId.PROCESS_VALIDATIONS
                  || phaseId == PhaseId.UPDATE_MODEL_VALUES)
          {
              processPartialExecute(viewRoot, phaseId);
          }
          else if (phaseId == PhaseId.RENDER_RESPONSE)
          {
              processPartialRendering(viewRoot, phaseId);
          }
      }
docs: process the partial response
  allowed phase ids according to the spec