private static void checkNamespaceAndPacakge(String name, InnerCNode configRoot, boolean isCpp) {
        if (isCpp && configRoot.defNamespace == null)
            throw new IllegalArgumentException("In config definition '" + name + "': A namespace is required");
       if (configRoot.defNamespace == null && configRoot.defPackage == null)
           throw new IllegalArgumentException("In config definition '" + name + "': A package (or namespace) is required");
    }
Generates the code and print it to this.out.
configgen/src/main/java/com/yahoo/config/codegen/MakeConfig.java