public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value) { if (value is string stringValue) { TypeConverterHelper currentHelper = helper; if (currentHelper == null) { IDestinationTypeProvider targetService = context.GetService(typeof(IDestinationTypeProvider)) as IDestinationTypeProvider; Type targetType = targetService.GetDestinationType(); if (!this.helpers.Value.TryGetValue(targetType, out currentHelper)) { currentHelper = GetTypeConverterHelper(targetType, this.baseType, this.helperType); if (!this.helpers.Value.TryAdd(targetType, currentHelper)) { if (!this.helpers.Value.TryGetValue(targetType, out currentHelper)) { throw FxTrace.Exception.AsError(new InvalidOperationException(SR.TypeConverterHelperCacheAddFailed(targetType))); } } } } object result = currentHelper.UntypedConvertFromString(stringValue, context); return(result); } return(base.ConvertFrom(context, culture, value)); }