public Builder setRequest(HttpRequest request) {
            this.request = request;
            return this;
        }
Prepares this for binary serialization.

This must be invoked after all changes have been made to this query before it is passed
on to a receiving backend. Calling it is somewhat expensive, so it should only happen once.
If a prepared query is cloned, it stays prepared.
container-search/src/main/java/com/yahoo/search/Query.java