C# PSCmdlet RuntimeDefinedParameter usage

gistfile1.cs

    [Cmdlet(VerbsData.Export, "AsQrCode")]
    public class ExportAsQrCode : PSCmdlet, IDynamicParameters
    {
        private static RuntimeDefinedParameterDictionary _staticStroage;
    
        public object GetDynamicParameters()
        {
            IEnumerable<string> brushes = typeof (Brushes).GetProperties().Select(x => x.Name);

            var runtimeDefinedParameterDictionary = new RuntimeDefinedParameterDictionary();
            var attributes = new Collection<Attribute>
            {
                new ParameterAttribute
                {
                    HelpMessage = "Brush"
                },
                new ValidateSetAttribute(brushes.ToArray()),
            };

            runtimeDefinedParameterDictionary.Add(DarkBrush, new RuntimeDefinedParameter(DarkBrush, typeof (string), attributes));
            runtimeDefinedParameterDictionary.Add(LightBrush, new RuntimeDefinedParameter(LightBrush, typeof (string), attributes));
            _staticStroage = runtimeDefinedParameterDictionary;

            return runtimeDefinedParameterDictionary;
        }
    }