Liskov's Substitution Principle

final Supplier<Map<String, FlightNode>> flightNodesSupplier = new TextFlightNodesSupplier(flightNodesFileName, delimiterPattern); // What if I don't want to read from a file? Okay, we can use SQLFlightNodesSupplier instead of TextFlightNodesSupplier.

final Supplier<List<FlightQuery>> flightQueriesSupplier = new TextFlightQueriesSupplier(pathsToCalculateFileName, delimiterPattern); // What if I don't want to read from a file? Okay, we can use SQLFlightQueriesSupplier instead of TextFlightQueriesSupplier.

final PathOutputter pathOutputter = new InOrderPathOutputter(); // What if I don't want to print out Source -> Destination, but instead want Destination -> Source? Okay, just use ReverseOrderPathOutputter instead of this.

final OutputterType outputterType = new FileOutputterType(outputFileName); // What if I don't want to write the output to the file and instead to the Console? Okay, just do ConsoleOutputterType instead.

final Project3 project3 = new Project3(flightNodesSupplier, flightQueriesSupplier, pathOutputter, outputterType);

project3.execute();