C# 自定义特性

 [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = true, Inherited = false)]
    public class LastModifiedAttribute : Attribute
    {
        private readonly DateTime _dateModified { get; private set; }
        private readonly string _changes { get; private set; }
        public LastModifiedAttribute(string dateModified, string changes)
        {
            _dateModified = DateTime.Parse(dateModified);
            _changes = changes;
        }
        public string Issues { get; set; }
    }

    [AttributeUsage(AttributeTargets.Assembly)]
    public class SupportsWhatsNewAttribute : Attribute
    { }