code: public ContextualStorage getContextualStorage(BeanManager beanManager, String flowClientWindowId)
      {
          ContextualStorage contextualStorage = storageMap.get(flowClientWindowId);
          if (contextualStorage == null)
          {
              synchronized (this)
              {
                  contextualStorage = storageMap.get(flowClientWindowId);
                  if (contextualStorage == null)
                  {
                      contextualStorage = new ContextualStorage(beanManager, true, true);
                      storageMap.put(flowClientWindowId, contextualStorage);
                  }
              }
          }
  
          return contextualStorage;
      }
docs: This method will return the ContextualStorage or create a new one
  if no one is yet assigned to the current flowClientWindowId.
  @param beanManager we need the CDI {@link BeanManager} for serialisation.
  @param flowClientWindowId the flowClientWindowId for the current flow.