* simpler way to test whether a {@code Class} instance is a member of this set is to call {@link
   * Class#isPrimitive}.
   *
   * @since 3.0
   */
  public static Set<Class<?>> allPrimitiveTypes() {
    return PRIMITIVE_TO_WRAPPER_TYPE.keySet();
  }

  /**
   * Returns an immutable set of all nine primitive-wrapper types (including {@link Void}).
   *
   * @since 3.0
   */

    assertThat(Primitives.unwrap(String.class)).isEqualTo(String.class);
  }

  public void testAllPrimitiveTypes() {
    Set<Class<?>> primitives = Primitives.allPrimitiveTypes();
    assertThat(primitives)
        .containsExactly(
            boolean.class,
            byte.class,
            char.class,
            double.class,
            float.class,
            int.class,

    assertThat(Primitives.unwrap(String.class)).isEqualTo(String.class);
  }

  public void testAllPrimitiveTypes() {
    Set<Class<?>> primitives = Primitives.allPrimitiveTypes();
    assertThat(primitives)
        .containsExactly(
            boolean.class,
            byte.class,
            char.class,
            double.class,
            float.class,
            int.class,

    assertFalse(TypeToken.of(Types.supertypeOf(Object[].class)).isArray());
  }

  public <T extends Integer> void testPrimitiveWrappingAndUnwrapping() {
    for (Class<?> type : Primitives.allPrimitiveTypes()) {
      assertIsPrimitive(TypeToken.of(type));
    }
    for (Class<?> type : Primitives.allWrapperTypes()) {
      assertIsWrapper(TypeToken.of(type));
    }

    assertFalse(TypeToken.of(Types.supertypeOf(Object[].class)).isArray());
  }

  public <T extends Integer> void testPrimitiveWrappingAndUnwrapping() {
    for (Class<?> type : Primitives.allPrimitiveTypes()) {
      assertIsPrimitive(TypeToken.of(type));
    }
    for (Class<?> type : Primitives.allWrapperTypes()) {
      assertIsWrapper(TypeToken.of(type));
    }