public void testHashMap() {
    HashMap<Integer, Integer> map = Maps.newHashMap();
    assertEquals(Collections.emptyMap(), map);
  }

  public void testHashMapWithInitialMap() {
    Map<String, Integer> original = new TreeMap<>();
    original.put("a", 1);
    original.put("b", 2);
    original.put("c", 3);
    HashMap<String, Integer> map = Maps.newHashMap(original);
    assertEquals(original, map);
  }

  public void testHashMap() {
    HashMap<Integer, Integer> map = Maps.newHashMap();
    assertEquals(Collections.emptyMap(), map);
  }

  public void testHashMapWithInitialMap() {
    Map<String, Integer> original = new TreeMap<>();
    original.put("a", 1);
    original.put("b", 2);
    original.put("c", 3);
    HashMap<String, Integer> map = Maps.newHashMap(original);
    assertEquals(original, map);
  }

            return new Object();
          }

          @Override
          public Map<Object, Object> loadAll(Iterable<?> keys) throws Exception {
            Map<Object, Object> result = Maps.newHashMap();
            for (Object key : keys) {
              Object value = new Object();
              result.put(key, value);
              // add extra entries
              result.put(value, key);
            }

            return new Object();
          }

          @Override
          public Map<Object, Object> loadAll(Iterable<?> keys) throws Exception {
            Map<Object, Object> result = Maps.newHashMap();
            for (Object key : keys) {
              Object value = new Object();
              result.put(key, value);
              // add extra entries
              result.put(value, key);
            }

     *            {@link HashMap}のキーの型
     * @param <V>
     *            {@link HashMap}の値の型
     * @return {@link HashMap}の新しいインスタンス
     * @see HashMap#HashMap()
     */
    public static <K, V> HashMap<K, V> newHashMap() {
        return new HashMap<>();
    }

    /**
     * {@link HashMap}の新しいインスタンスを作成して返します。
     *
     * @param <K>
     *            {@link HashMap}のキーの型
     * @param <V>

    }

    ImmutableList<K> collectTypes(Iterable<? extends K> types) {
      // type -> order number. 1 for Object, 2 for anything directly below, so on so forth.
      Map<K, Integer> map = Maps.newHashMap();
      for (K type : types) {
        collectTypes(type, map);
      }
      return sortKeysByValue(map, Ordering.natural().reverse());
    }

    assertHasArrayInterfaces(new TypeToken<NoInterface[]>() {});
  }

  public void testGetGenericInterfaces_withInterfaces() {
    Map<Class<?>, Type> interfaceMap = Maps.newHashMap();
    for (TypeToken<?> interfaceType :
        new TypeToken<Implementation<Integer, String>>() {}.getGenericInterfaces()) {
      interfaceMap.put(interfaceType.getRawType(), interfaceType.getType());
    }

    assertHasArrayInterfaces(new TypeToken<NoInterface[]>() {});
  }

  public void testGetGenericInterfaces_withInterfaces() {
    Map<Class<?>, Type> interfaceMap = Maps.newHashMap();
    for (TypeToken<?> interfaceType :
        new TypeToken<Implementation<Integer, String>>() {}.getGenericInterfaces()) {
      interfaceMap.put(interfaceType.getRawType(), interfaceType.getType());
    }