What version of Java did you use on the project? Did you use streams?

Java 11 was used on the project because it combines stability and modern language features. Streams were actively used for collection processing and simplifying code, for example, for filtering and transforming lists:

List<String> filtered = list.stream()
    .filter(s -> s.startsWith("A"))
    .map(String::toUpperCase)
    .collect(Collectors.toList());