code: public static Constraint future() {
  		return new Constraint("future", simplePayload("future")) {
  			public boolean isValid(Object actualValue) {
  				if (actualValue != null) {
  					long now = System.currentTimeMillis();
  					if ((actualValue instanceof Date && ((Date) actualValue).getTime() <= now)
  							|| (actualValue instanceof Number && ((Number) actualValue).longValue() <= now)) {
  						return false;
  					}
  				}
  				return true;
  			}
  		};
  	}
docs: The 'future' constraint - field value must be a {@link Date} or a timestamp in the future.
  @return constraint