if (handleNullAutomatically) {
      // TODO(kevinb): we shouldn't be checking for a null result at runtime. Assert?
      return b == null ? null : checkNotNull(doBackward(b));
    } else {
      return unsafeDoBackward(b);
    }
  }

  /*
   * LegacyConverter violates the contract of Converter by allowing its doForward and doBackward