The aerogear-unifiedpush-java-client send method receives a MessageResponseCallback which exposes the HTTP status code for the request made. In order to continue using the UnexpectedResponseException.verifyResponse, I had to mock the restassured Response since there is not an available constructor to use for creating an instance. The best practice would be to avoid carrying the restassured Response outside the sender classes. A custom Value Object which will wrap the restassured Response should be used as a data transfer object inside the integration suite. It's always better to avoid relying on the responses of third party libraries.