public DistanceMatrixApiRequest arrivalTime(Instant arrivalTime) {
    return param("arrival_time", Long.toString(arrivalTime.toEpochMilli() / 1000L));
  }
Specifies the desired time of arrival for transit requests. You can specify either
departure_time or arrival_time, but not both.

@param arrivalTime The preferred arrival time.
@return Returns this {@code DistanceMatrixApiRequest} for call chaining.
src/main/java/com/google/maps/DistanceMatrixApiRequest.java