Java Stream Collectors.toMap value is a Set

Question

I want to use a Java Stream to run over a List of POJOs, such as the list List below, and transform it into a Map Map>

Answer 1

Same Same But Different

Map> m = new HashMap<>();

as.forEach(a -> {
    m.computeIfAbsent(a.name, v -> new HashSet<>())
            .add(a.property);
    });