code: public static Instant randomInstantBefore(Instant before) {
      checkArgument(before != null, "Before must be non-null");
      checkArgument(before.isAfter(MIN_INSTANT), "Cannot produce date before %s", MIN_INSTANT);
      return randomInstant(MIN_INSTANT, before);
    }
docs: Returns a random {@link Instant} that is before the given {@link Instant}.
  
  @param before the value that returned {@link Instant} must be before
  @return the random {@link Instant}
  @throws IllegalArgumentException if before is null or if before is equal to or before {@link
  RandomDateUtils#MIN_INSTANT}