code: public static Date randomDateAfter(Date after) {
      checkArgument(after != null, "After must be non-null");
      Instant instant = randomInstantAfter(after.toInstant());
      return Date.from(instant);
    }
docs: Returns a random {@link Date} that is after the given {@link Date}.
  
  @param after the value that returned {@link Date} must be after
  @return the random {@link Date}
  @throws IllegalArgumentException if after is null or if after is equal to or after {@link
  RandomDateUtils#MAX_INSTANT}