Map<Integer, Integer> immutableEmptyMap = Map.of();
Map<Integer, Integer>.Map<Integer, Integer> immutableMap = Map.of(1, 2, 3, 4);
Map<Integer, Integer> with two initial key-value entries.Map<Integer, Integer> immutableMap = Map.ofEntries(Map.entry(1, 2), Map.entry(3, 4));
Map<Integer, Integer> with two initial key-value entries.Map<Integer, Integer> mutableMap = new HashMap<>(immutableMap);
Map<Integer, Integer> from an immutable Map<Integer, Integer>.