private IEnumerable<Shelveset> GetPastShelvesets(VersionControlServer service, Workspace workspace)
        {
            var pastShelvesets = service.QueryShelvesets(null, workspace.OwnerName).Where(s => s.Comment != null && s.Comment.Contains(_extensionName));
            if (pastShelvesets != null && pastShelvesets.Count() > 0)
            {
                if (IsWorkspaceSpecificShelvesetName)
                {
                    pastShelvesets = pastShelvesets.Where(s => s.Name.Contains(workspace.Name));
                }
                return pastShelvesets.OrderByDescending(s => s.CreationDate);
            }
            else
            {
                return pastShelvesets;
            }

        }