public ApplicationSpec add(ApplicationSpec app) {
        for (Map.Entry<String, HashSet<String>> entry : app.services.entrySet()) {
            String protocol = entry.getKey();
            for (String service : entry.getValue()) {
                addService(protocol, service);
            }
        }
        return this;
    }
Adds the content of the given application to this.

@param app The application whose content to copy.
@return This, to allow chaining.
messagebus/src/main/java/com/yahoo/messagebus/routing/ApplicationSpec.java