Why EncodeException's message is not nullable in 1st constructor but nullable in 2nd constructor?

[vvy]

  /**
   * @param message the reason for the failure.
   */
  public EncodeException(String message) {
    super(-1, checkNotNull(message, "message"));
  }

  /**
   * @param message possibly null reason for the failure.
   * @param cause the cause of the error.
   */
  public EncodeException(String message, Throwable cause) {
    super(-1, message, checkNotNull(cause, "cause"));
  }

It seems like that EncodeException's message is not null in 1st constructor,
BUT, when a exception with null message is throw (eg. new NegativeArraySizeException() ), you will get a null message EncodeException, such as below codes in RequestTemplateFactoryResolver.

    protected RequestTemplate resolve(Object[] argv, RequestTemplate mutable,
                                      Map<String, Object> variables) {
      Object body = argv[metadata.bodyIndex()];
      checkArgument(body != null, "Body parameter %s was null", metadata.bodyIndex());
      try {
        encoder.encode(body, metadata.bodyType(), mutable);
      } catch (EncodeException e) {
        throw e;
      } catch (RuntimeException e) {
        throw new EncodeException(e.getMessage(), e);
      }
      return super.resolve(argv, mutable, variables);
    }