public Task <ApplicationUser> FindByIdAsync(string userId, CancellationToken cancellationToken = default(CancellationToken))
{
cancellationToken.ThrowIfCancellationRequested();
var isValidGuid = Guid.TryParse(userId, out var userGuid);
if (!isValidGuid)
{
return(Task.FromResult <ApplicationUser>(null));
}
return(_usersTable.FindByIdAsync(userGuid));
}