feat: Add byPrimaryKey and getKeyColumnNames methods to GtfsTableContainer

[aababilov]

These methods will be used by translations validator.

Sample code for GtfsStopTimeTableContainer.

  private void setupIndices(NoticeContainer noticeContainer) {
    for (GtfsStopTime newEntity : entities) {
      CompositeKey key = new CompositeKey(newEntity.tripId(), newEntity.stopSequence());
      GtfsStopTime oldEntity = byTripIdAndStopSequenceMap.getOrDefault(key, null);
      if (oldEntity != null) {
        noticeContainer.addValidationNotice(
            new DuplicateKeyNotice(
                gtfsFilename(),
                newEntity.csvRowNumber(),
                oldEntity.csvRowNumber(),
                GtfsStopTimeTableLoader.TRIP_ID_FIELD_NAME,
                oldEntity.tripId(),
                GtfsStopTimeTableLoader.STOP_SEQUENCE_FIELD_NAME,
                oldEntity.stopSequence()));
      } else {
        byTripIdAndStopSequenceMap.put(key, newEntity);
      }
    }
    for (GtfsStopTime entity : entities) {
      byTripIdMap.put(entity.tripId(), entity);
    }
    for (List<GtfsStopTime> entityList : Multimaps.asMap(byTripIdMap).values()) {
      entityList.sort(
          (entity1, entity2) -> Integer.compare(entity1.stopSequence(), entity2.stopSequence()));
    }
    for (GtfsStopTime entity : entities) {
      byStopIdMap.put(entity.stopId(), entity);
    }
  }

  @Override
  public ImmutableList<String> getKeyColumnNames() {
    return GtfsStopTimeTableLoader.KEY_COLUMN_NAMES;
  }

  @Override
  public Optional<GtfsStopTime> byPrimaryKey(String id, String subId) {
    try {
      return Optional.ofNullable(
          byTripIdAndStopSequenceMap.getOrDefault(
              new CompositeKey(id, Integer.parseInt(subId)), null));
    } catch (NumberFormatException e) {
      return Optional.empty();
    }
  }

  static class CompositeKey {
    private final String firstKey;

    private final int sequenceKey;

    CompositeKey(String firstKey, int sequenceKey) {
      this.firstKey = firstKey;
      this.sequenceKey = sequenceKey;
    }

    @Override
    public boolean equals(Object obj) {
      if (obj == this) {
        return true;
      }
      if (obj instanceof CompositeKey) {
        CompositeKey other = (CompositeKey) obj;
        return Objects.equals(firstKey, other.firstKey) && sequenceKey == other.sequenceKey;
      }
      return false;
    }

    @Override
    public int hashCode() {
      return Objects.hash(firstKey, sequenceKey);
    }
  }

[isabelle-dr]

🎉🎉🎉 ----> 1000th PR! <----- 🎉🎉🎉

[lionel-nj]

Thanks @aababilov, LGTM!