}
    return this;
  }

  private boolean isWrapper() {
    return Primitives.allWrapperTypes().contains(runtimeType);
  }

  /**
   * Returns the corresponding primitive type if this is a wrapper type; otherwise returns {@code
   * this} itself. Idempotent.
   *
   * @since 15.0
   */
  public final TypeToken<T> unwrap() {
    if (isWrapper()) {