refactor flag names - make it more explicitly

avoid the using 'reflect' package while getting flag names

flag.go

@@ -203,12 +203,9 @@ func withEnvHint(envVars []string, str string) string {
 	return str + envText
 }
 
-func flagNames(f Flag) []string {
+func flagNames(name string, aliases []string) []string {
 	var ret []string
 
-	name := flagStringField(f, "Name")
-	aliases := flagStringSliceField(f, "Aliases")
-
 	for _, part := range append([]string{name}, aliases...) {
 		// v1 -> v2 migration warning zone:
 		// Strip off anything after the first found comma or space, which
@@ -231,17 +228,6 @@ func flagStringSliceField(f Flag, name string) []string {
 	return []string{}
 }
 
-func flagStringField(f Flag, name string) string {
-	fv := flagValue(f)
-	field := fv.FieldByName(name)
-
-	if field.IsValid() {
-		return field.String()
-	}
-
-	return ""
-}
-
 func withFileHint(filePath, str string) string {
 	fileText := ""
 	if filePath != "" {