Maps: Map.copyOf snapshots, unmodifiableMap wraps

Map<String, Integer> source = new TreeMap<>();
source.put("a", 1);

Map<String, Integer> snapshot = Map.copyOf(source);
Map<String, Integer> view = Collections.unmodifiableMap(source);

source.put("b", 2);
System.out.println("copyOf snapshot   : " + new TreeMap<>(snapshot));
System.out.println("unmodifiable view : " + view);

copyOf snapshot   : {a=1}
unmodifiable view : {a=1, b=2}