code: public LocalTime getStartTimeForTrips (Collection<Trip> trips) {
          int earliestDeparture = Integer.MAX_VALUE;
  
          for (Trip trip : trips) {
              StopTime st = feed.getOrderedStopTimesForTrip(trip.trip_id).iterator().next();
              int dep = st.departure_time;
  
              // these trips begin on the next day, so we need to cast them to 0 - 86399
              if (dep > 86399) {
                  dep = dep % 86399;
              }
  
              if (dep <= earliestDeparture) {
                  earliestDeparture = dep;
              }
          }
          return LocalTime.ofSecondOfDay(earliestDeparture);
      }
docs: Get earliest departure time for a set of trips.
  @param trips
  @return earliest departure time