using System;
using System.Linq;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Reflection;
 
public static class Ext {
	public static IList<T> GetItems<T>(this ReadOnlyCollection<T> roc) {
		var prop = roc.GetType().GetProperties(BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static ).FirstOrDefault(x => x.Name.Contains("Items"));
		return (IList<T>)prop.GetValue(roc, null);
	}
}
 
public class Test
{
	static List<int> l = new List<int> {1,2,3};
	static ReadOnlyCollection<int> Get()
	{
		return new ReadOnlyCollection<int>(l);
	}
 
	public static void Main()
	{
		var list = Get().GetItems();
		list.Add(3);
		Console.WriteLine(l.Count());
	}
}

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