3-4: routesByAirline.java

@RequestMapping("/routes")
public ResponseEntity<List<String>> routesByAirline(@RequestParam String airline) {
  N1qlQuery query = N1qlQuery.simple(select(
    arrayLength("schedule").as("num_routes"),
    x("sourceairport").as("source"),
    x("destinationairport").as("dest"),
    x("airline")
  ).from(i(bucket.name())).where(
    x("type").eq(s("route"))
    .and(x("airline").eq(s(airline)))
  ).orderBy(asc("source")));

  List<String> destinations = new ArrayList<>();
  bucket.query(query).forEach(row -> {
    JsonObject value = row.value();
    destinations.add(String.format("%s -> %s, %d",
        value.get("source"), value.get("dest"), value.get("num_routes")));
    });
  return new ResponseEntity<List<String>>(destinations, HttpStatus.OK);
}