@Override
        public LeafCNode setDefaultValue(DefaultValue defaultValue) {
            if (defaultValue != null)
                throw new IllegalArgumentException("Parameters of type '" + getType() + "' cannot have a default value.");
            return this;
        }
Superclass for no-class leaf nodes that cannot have a default.
configgen/src/main/java/com/yahoo/config/codegen/LeafCNode.java