public ServerBuilder requestIdGenerator(
            Function<? super RoutingContext, ? extends RequestId> requestIdGenerator) {
        virtualHostTemplate.requestIdGenerator(requestIdGenerator);
        return this;
    }
Sets the {@link Function} that generates a {@link RequestId} for each {@link Request}.
By default, a {@link RequestId} is generated from a random 64-bit integer.

@see RequestContext#id()
core/src/main/java/com/linecorp/armeria/server/ServerBuilder.java