Add support for serializing elements using InnerXml about dart-xml-serializable HOT 7 CLOSED

@annotation.XmlSerializable()
class Example {
  @annotation.XmlElement()
  @_CustomDateTimeConverter()
  final DateTime a;

  ...
}

class _CustomDateTimeConverter implements annotation.XmlElementConverter<DateTime> {
  const _CustomDateTimeConverter();

  @override
  DateTime fromXmlElement(XmlElement element) => DateTime(
    int.parse(element.getElement('year')!.getText()!),
    int.parse(element.getElement('month')!.getText()!),
    int.parse(element.getElement('day')!.getText()!),
  );

  @override
  XmlElement toXmlElement(DateTime object) => XmlElement(
    XmlName('???'),
    [],
    [
      XmlElement(XmlName('year'), [], [XmlText(object.year.toString())]),
      XmlElement(XmlName('month'), [], [XmlText(object.month.toString())]),
      XmlElement(XmlName('day'), [], [XmlText(object.day.toString())]),
    ],
  );
}

@annotation.XmlRootElement(name: 'title')
@annotation.XmlSerializable()
class Title {
  @annotation.XmlAttribute(name: 'lang')
  String? language;

  @InnerXmlConverter() // changed this line
  @annotation.XmlElement() // changed this line
  String? text;

  Title({
    this.language,
    this.text,
  });

  factory Title.fromXmlElement(XmlElement element) =>
      _$TitleFromXmlElement(element);

  @override
  String toString() {
    return 'Title{language: $language, text: $text}';
  }

  void buildXmlChildren(
    XmlBuilder builder, {
    Map<String, String> namespaces = const {},
  }) =>
      _$TitleBuildXmlChildren(
        this,
        builder,
        namespaces: namespaces,
      );

  void buildXmlElement(
    XmlBuilder builder, {
    Map<String, String> namespaces = const {},
  }) =>
      _$TitleBuildXmlElement(
        this,
        builder,
        namespaces: namespaces,
      );
....
....
....
.... rest of the code same as example from xml_annotation.

import 'package:xml/xml.dart';
import 'package:xml_annotation/xml_annotation.dart' as annotation;

class InnerXmlConverter implements annotation.XmlConverter<String> {
  const InnerXmlConverter();

  @override
  void buildXmlChildren(
    String instance,
    XmlBuilder builder, {
    Map<String, String> namespaces = const {},
  }) {
    builder.xml(instance);
  }

  @override
  String fromXmlElement(
    XmlElement? element,
  ) {
    return element?.innerXml ?? '';
  }

  @override
  List<XmlAttribute> toXmlAttributes(
    String instance, {
    Map<String, String?> namespaces = const {},
  }) {
    return <XmlAttribute>[];
  }

  @override
  List<XmlNode> toXmlChildren(
    String instance, {
    Map<String, String?> namespaces = const {},
  }) {
    return <XmlNode>[XmlText(instance)];
  }
}