docs: public ViewScopeContextualStorage getContextualStorage(
          BeanManager beanManager, String viewScopeId)
      {
          ViewScopeContextualStorage contextualStorage = storageMap.get(viewScopeId);
          if (contextualStorage == null)
          {
              synchronized (this)
              {            
                  contextualStorage = storageMap.get(viewScopeId);
                  if (contextualStorage == null)
                  {            
                      contextualStorage = new ViewScopeContextualStorage(beanManager);
                      storageMap.put(viewScopeId, contextualStorage);
                  }
              }
          }
          return contextualStorage;
      }