I found the solution from Rest client using Android-Annotations.
Like the GET requests, it is extremely simple to send POST requests using Android-Annotations. One difference is that you need to define the parameters that you are going to send as a custom class (e.g. Event class in the example below) or if you want to control this dynamically, then a Map (e.g. a MultiValueMap). The url for the request can still be constructed in a similar fashion using the variables enclosed inside {...} and the response can be handled similarly as in GET requests.
@Post("/events")
void addEvent(Event event);
@Post("/events/{id}")
void addEventById(Event event, long id);
@Post("/authenticate/event/")
Object authenticateEventData(MultiValueMap data);