.NET (Core and Framework)

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using System;
using System.Reflection;
 
public sealed class CurrentTimeZone
{
    private const int RefreshAfterMinutes = 5;
    private static readonly object _lockMe = new object();
    private static readonly Type _timeZoneType;
    private static readonly ConstructorInfo _timeZoneConstructor;
    private static TimeZone _instance = TimeZone.CurrentTimeZone;
    private static DateTime _instanceCreated = DateTime.UtcNow;
    
    static CurrentTimeZone()
    {
        _timeZoneType = TimeZone.CurrentTimeZone.GetType();
        _timeZoneConstructor = _timeZoneType.GetConstructor(
            BindingFlags.Instance | BindingFlags.NonPublic,
            null, new Type[0], null);
    }
    
    private static TimeZone CreateInstance()
    {
        return (TimeZone)_timeZoneConstructor.Invoke(null);
    }
    
    private static void UpdateIfStale()
    {
        TimeSpan age = _instanceCreated - DateTime.UtcNow;
        if (age.TotalMinutes > RefreshAfterMinutes)
        {
            _instance = CreateInstance();
            _instanceCreated = DateTime.UtcNow;
        }
    }
    
    public static TimeZone Instance
    {
        get
        {
            lock(_lockMe)
            {
                UpdateIfStale();
                return _instance;
            }
        }
    }
    
    public static void Refresh()
    {
        lock(_lockMe)
        {
            _instance = CreateInstance();
            _instanceCreated = DateTime.UtcNow;
        }
    }
}