code: public final TypeToken<T> unwrap() {
      if (isWrapper()) {
        @SuppressWarnings("unchecked") // this is a wrapper class
        Class<T> type = (Class<T>) runtimeType;
        return of(Primitives.unwrap(type));
      }
      return this;
    }
docs: Returns the corresponding primitive type if this is a wrapper type; otherwise returns {@code
  this} itself. Idempotent.
  
  @since 15.0