protected boolean isRequestReplayable() {
        if (startedSendingResponseToClient) {
            NO_RETRY_RESP_STARTED.increment();
            return false;
        }
        if (!zuulRequest.hasCompleteBody()) {
            NO_RETRY_INCOMPLETE_BODY.increment();
            return false;
        }
        return true;
    }
Request is replayable on a different origin IFF
A) we have not started to send response back to the client  AND
B) we have not lost any of its body chunks
zuul-core/src/main/java/com/netflix/zuul/filters/endpoint/ProxyEndpoint.java