private void verifyInnerArray(String id) {
        String message = "No such inner array in " + verifyWarning(id);
        if ( ! innerArrayDefs.containsKey(id)) {
            if (arrayDefs.containsKey(id))
                message += ". However, the definition does contain an array with the same name";
            throw new IllegalArgumentException(message);
        }
    }
Throws if the given value is not legal.
config/src/main/java/com/yahoo/vespa/config/ConfigDefinition.java