Сериализация массива коллекций ObservableCollection в xml

public ObservableCollection<MyClass> Collection1 { get; set; }
public ObservableCollection<MyClass> Collection2 { get; set; }
public ObservableCollection<MyClass> Collection3 { get; set; }

            XmlSerializer xmlFormater = new XmlSerializer(typeof(ObservableCollection<MyClass>));
            using (var file = new FileStream("Collection1.xml", FileMode.OpenOrCreate))
            {
                xmlFormater.Serialize(file, Collection1);
            }
 
            // И аналогично другие коллекции.

public ObservableCollection<MyClass>[] AllCollections = new ObservableCollection<MyClass>[3];
AllCollections[0] = Collection1;
AllCollections[1] = Collection2;
AllCollections[2] = Collection3;

            XmlSerializer xmlFormater = new XmlSerializer(typeof(ObservableCollection<MyClass>[]));
            using (var file = new FileStream("AllCollections.xml", FileMode.OpenOrCreate))
            {
                xmlFormater.Serialize(file, AllCollections);
            }

using System;
 
namespace SerializationTest
{
    [Serializable]
    public class MyClass
    {
        public MyClass() {}
 
        public string ParamName { get; set; }
 
        public string ParamValue { get; set; }
    }
}

using System.Collections.ObjectModel;
using System.IO;
using System.Windows;
using System.Xml.Serialization;
 
namespace SerializationTest
{
    /// <summary>
    /// Логика взаимодействия для MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public ObservableCollection<MyClass> Collection1 { get; set; }
        public ObservableCollection<MyClass> Collection2 { get; set; }
 
        public ObservableCollection<MyClass>[] AllCollections = new ObservableCollection<MyClass>[2];
 
        public MainWindow()
        {
            InitializeComponent();
 
            Collection1 = new ObservableCollection<MyClass>
            {
                new MyClass { ParamName = "1", ParamValue = "2" },
                new MyClass { ParamName = "3", ParamValue = "4" }
            };
 
            Collection2 = new ObservableCollection<MyClass>
            {
                new MyClass { ParamName = "5", ParamValue = "6" },
                new MyClass { ParamName = "7", ParamValue = "8" }
            };
 
            AllCollections[0] = Collection1;
            AllCollections[1] = Collection2;
 
            XmlSerializer xmlFormater = new XmlSerializer(typeof(ObservableCollection<MyClass>[]));
            using (var file = new FileStream("AllCollections.xml", FileMode.OpenOrCreate))
            {
                xmlFormater.Serialize(file, AllCollections);
            }
 
        }
    }
}