public VirtualHostBuilder requestIdGenerator(
            Function<? super RoutingContext, ? extends RequestId> requestIdGenerator) {
        this.requestIdGenerator = requireNonNull(requestIdGenerator, "requestIdGenerator");
        return this;
    }
Sets the {@link Function} which generates a {@link RequestId}.
If not set, the value set via {@link ServerBuilder#requestIdGenerator(Function)} is used.

@param requestIdGenerator the {@link Function} which generates a {@link RequestId}
@see RequestContext#id()
core/src/main/java/com/linecorp/armeria/server/VirtualHostBuilder.java