Add comment for new exported func and const

aws/accountid/account_id.go

@@ -8,6 +8,7 @@ import (
 	"github.com/aws/smithy-go/auth"
 )
 
+// AccountID retrieves the accountID from identity or ignores that depending on accountID endpoint mode
 func AccountID(identity auth.Identity, mode accountidmode.AIDMode) *string {
 	if ca, ok := identity.(*smithy.CredentialsAdapter); ok && (mode == accountidmode.Preferred || mode == accountidmode.Required) {
 		return aws.String(ca.Credentials.AccountID)
@@ -16,6 +17,8 @@ func AccountID(identity auth.Identity, mode accountidmode.AIDMode) *string {
 	return nil
 }
 
+// CheckAccountID checks accountID mode in case the required accountID misses or
+// accountID endpoint mode is configured with invalid value
 func CheckAccountID(identity auth.Identity, mode accountidmode.AIDMode) error {
 	switch mode {
 	case "":

aws/accountid/mode/mode.go

@@ -5,12 +5,14 @@ import "fmt"
 // AIDMode switches on/off the account ID based endpoint routing
 type AIDMode string
 
+// enums of valid AIDMode
 const (
 	Preferred AIDMode = "preferred"
 	Required  AIDMode = "required"
 	Disabled  AIDMode = "disabled"
 )
 
+// SetFromString converts config string to corresponding AIDMode or reports error if the value is not enumerated
 func (mode *AIDMode) SetFromString(s string) error {
 	switch {
 	case s == "preferred":