HTTP server following the spec can omit the body from a GET request.
> A payload within a GET request message has no defined semantics;
> sending a payload body on a GET request might cause some existing
> implementations to reject the request.
if the request method does not include defined semantics for an entity-body, then the message-body SHOULD be ignored when handling the request.
Now, RFC 2616 is obsolete, and I couldn't find such explicit wording in the superseding RFC 7231. But §4.3.1 (https://tools.ietf.org/html/rfc7231#section-4.3.1) says:
A payload within a GET request message has no defined semantics; sending a payload body on a GET request might cause some existing implementations to reject the request.