class XmlDeclarationImpl implements XmlDeclaration {

    private final List<Attribute> attributes;

    public XmlDeclarationImpl() {
        this.attributes = new ArrayList<>();
    }

    @Override
    public List<Attribute> attributes() {
        return attributes;
    }

    @Override
    public String toString() {<FILL_FUNCTION_BODY>}
}

        return "<?xml " + attributes().stream()
            .map(a -> ".")
            .collect(joining("", " ", "")) + 
            "?>";
    
<no_super_class>