code: public long getWorkspaceDataSizeDirectly() throws QuotaManagerException
     {
        try
        {
           return dataManager.getWorkspaceDataSize();
        }
        catch (RepositoryException e)
        {
           throw new QuotaManagerException(e.getMessage(), e);
        }
     }
docs: Calculate workspace data size by asking directly respective {@link WorkspacePersistentDataManager}.