private Resolver selectResolver(Query query) {
        String resolverId = query.properties().getString(pageResolverName);
        if (resolverId == null) return resolverRegistry.defaultResolver();
        Resolver resolver = resolverRegistry.getComponent(resolverId);
        if (resolver == null) throw new IllegalInputException("No page template resolver '" + resolverId + "'");
        return resolver;
    }
Returns the list of page templates specified in the query, or the default if none, or the
empty list if no default, never null.
container-search/src/main/java/com/yahoo/search/pagetemplates/PageTemplateSearcher.java