Should set UnderlyingType when use Template

Author: scott-xu

src/CommandLineUtils/Attributes/OptionAttribute.cs

@@ -82,10 +82,11 @@ internal CommandOption Configure(CommandLineApplication app, PropertyInfo prop)
                     LongName = longName,
                     ShortName = longName.Substring(0, 1),
                     ValueName = prop.Name.ToConstantCase(),
-                    UnderlyingType = prop.PropertyType,
                 };
             }
 
+            option.UnderlyingType = prop.PropertyType;
+
             Configure(option);
 
             option.Description ??= prop.Name;

test/CommandLineUtils.Tests/DefaultHelpTextGeneratorTests.cs

@@ -216,6 +216,9 @@ SomeNullableEnumArgument          nullable enum arg desc.
                                     Allowed values are: None, Normal, Extreme.
   -enumOpt4|--verb4[:<VERB4>]       nullable enum option desc.
                                     Allowed values are: None, Normal, Extreme.
+  -enumOpt5|--verb5 <VERB5>         enum option desc.
+                                    Allowed values are: None, Normal, Extreme.
+                                    Default value is: None.
   -?|-h|--help                      Show help information.
 
 ",
@@ -255,6 +258,9 @@ public class MyApp
             [Option(CommandOptionType.SingleOrNoValue, ShortName = "enumOpt4", Description = "nullable enum option desc.")]
             public SomeEnum? Verb4 { get; set; }
 
+            [Option("-enumOpt5 | --verb5 <VERB5>", Description = "enum option desc.")]
+            public SomeEnum Verb5 { get; set; }
+
             [Argument(0, Description = "string arg desc.")]
             public string SomeStringArgument { get; set; }