Method unmodifiableNavigableMap

output/java_guava/1.4.19/Maps.java:3244–3252

Returns an unmodifiable view of the specified navigable map. Query operations on the returned map read through to the specified map, and attempts to modify the returned map, whether direct or via its views, result in an UnsupportedOperationException. The returned navigable map will be se

(NavigableMap<K, V> map)

   */

  @GwtIncompatible // NavigableMap
  public static <K, V> NavigableMap<K, V> unmodifiableNavigableMap(NavigableMap<K, V> map) {
    checkNotNull(map);
    if (map instanceof UnmodifiableNavigableMap) {
      return map;
    } else {
      return new UnmodifiableNavigableMap<K, V>(map);
    }
  }

  @Nullable
  private static <K, V> Entry<K, V> unmodifiableOrNull(@Nullable Entry<K, V> entry) {