It is somewhat difficult to keep time in sync in distributed systems. Picking a (lets say "now at the wall clock") time at the client (which could be a browser that we have no control over) and instantly sending it to the backend can easily cause constraint validation for Future/FutureOrPresent constraint violations in one or Past/PastOrPresent constraint violations in the other direction. It would be nice if it would be possible to specify a skewTolerance-Duration as optional parameter for time based constraints or as a global validator property/ or property of the clock provider.

What do you think about something like?

@FutureOrPresent(skewTolerance=@Tolerance(amount=5, unit=TimeUnit.SECONDS))