code: private static TransactionManager getTransactionManagerFromCache(WorkspaceStorageCache cache)
     {
        try
        {
           return (TransactionManager)cache.getClass().getMethod("getTransactionManager", (Class<?>[])null)
              .invoke(cache, (Object[])null);
        }
        catch (Exception e)
        {
           LOG.debug("Could not get the transaction manager from the cache", e);
        }
        return null;
     }
docs: Try to get the TransactionManager from the cache by calling by reflection
  getTransactionManager() on the cache instance, by default it will return null