In MessageDispatcher::sendMessageWithFuture there are some validations to check the case of RequestOptions options being null. However, if one calls that method with a null RequestOptions argument, the execution ends in failure (with a NPE in the resulting future) [1].
The point is, either the validations are unnecessary and should exist a preconditions check at the beginning of the method, or it should set a (documented) default RequestOptions so the sending can be completed.

[1] the source of the NPE is UnicastRequest::sendRequest when trying to access the RequestOptions's getMode method.