private final boolean allowNullInput;
    private final NotationParser<N, T> delegate;

    public ErrorHandlingNotationParser(Object targetTypeDisplayName, String invalidNotationMessage, boolean allowNullInput, NotationParser<N, T> delegate) {
        this.targetTypeDisplayName = targetTypeDisplayName;
        this.invalidNotationMessage = invalidNotationMessage;
        this.allowNullInput = allowNullInput;

     *
     * TODO - attach the null safety to each converter and infer whether null is a valid input or not.
     */
    public NotationParserBuilder<N, T> allowNullInput() {
        allowNullInput = true;
        return this;
    }

    /**
     * Adds a converter to use to parse notations. Converters are used in the order added.
     */

    }

    public static NotationParser<Object, String> parser() {
        return NotationParserBuilder
                .toType(String.class)
                .noImplicitConverters()
                .allowNullInput()
                .converter(new PathNotationConverter())
                .toComposite();
    }

    @Override

    }

    def "can opt in to allow null as input"() {
        def converter = Mock(NotationConverter)
        def parser = NotationParserBuilder
                .toType(String.class)
                .allowNullInput()
                .converter(converter)
                .toComposite()


        given:
        converter.convert(null, _) >> { Object n, NotationConvertResult result -> result.converted("[null]") }