private static class NullType extends Type {

        public NullType() {
            super("Bez typu");
        }

        @Override
        public int hashCode() {
            return 1;
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj)
                return true;
            if (obj == null)
                return false;
            if (obj instanceof NullType)
                return true;

            return false;
        }
    }