Revert "Add sso token provider"

CHANGELOG_PENDING.md

@@ -3,5 +3,3 @@
 ### SDK Enhancements
 
 ### SDK Bugs
-* `aws/credentials/ssocreds`: Implement SSO token provider to support for `sso-session` in AWS shared config.
-  * Fixes [4649](https://github.com/aws/aws-sdk-go/issues/4649)

aws/credentials/ssocreds/provider.go

@@ -4,6 +4,7 @@ import (
 	"crypto/sha1"
 	"encoding/hex"
 	"encoding/json"
+	"fmt"
 	"io/ioutil"
 	"path/filepath"
 	"strings"
@@ -122,6 +123,25 @@ func getCacheFileName(url string) (string, error) {
 	return strings.ToLower(hex.EncodeToString(hash.Sum(nil))) + ".json", nil
 }
 
+type rfc3339 time.Time
+
+func (r *rfc3339) UnmarshalJSON(bytes []byte) error {
+	var value string
+
+	if err := json.Unmarshal(bytes, &value); err != nil {
+		return err
+	}
+
+	parse, err := time.Parse(time.RFC3339, value)
+	if err != nil {
+		return fmt.Errorf("expected RFC3339 timestamp: %v", err)
+	}
+
+	*r = rfc3339(parse)
+
+	return nil
+}
+
 type token struct {
 	AccessToken string  `json:"accessToken"`
 	ExpiresAt   rfc3339 `json:"expiresAt"`