Limit iso8601 fractional second precision to milliseconds (#3507)

Author: skmcgrail

CHANGELOG_PENDING.md

@@ -3,3 +3,5 @@
 ### SDK Enhancements
 
 ### SDK Bugs
+* `private/protocol`: Limit iso8601 fractional second precision to milliseconds ([#3507](https://github.com/aws/aws-sdk-go/pull/3507))
+ * Fixes [#3498](https://github.com/aws/aws-sdk-go/issues/3498)

private/protocol/timestamp.go

@@ -27,7 +27,7 @@ const (
 // RFC3339 a subset of the ISO8601 timestamp format. e.g 2014-04-29T18:30:38Z
 ISO8601TimeFormat = "2006-01-02T15:04:05.999999999Z"
 
-// This format is used for output time without seconds precision
+// This format is used for output time with fractional second precision up to milliseconds
 ISO8601OutputTimeFormat = "2006-01-02T15:04:05.999999999Z"
 )
 
@@ -48,7 +48,7 @@ func IsKnownTimestampFormat(name string) bool {
 
 // FormatTime returns a string value of the time.
 func FormatTime(name string, t time.Time) string {
-t = t.UTC()
+t = t.UTC().Truncate(time.Millisecond)
 
 switch name {
 case RFC822TimeFormatName:

private/protocol/timestamp_test.go

@@ -38,6 +38,11 @@ func TestFormatTime(t *testing.T) {
 expectedOutput: "2000-01-02T20:34:56.123Z",
 input: time.Date(2000, time.January, 2, 20, 34, 56, .123e9, time.UTC),
 },
+"ISO8601Test3": {
+formatName: ISO8601TimeFormatName,
+expectedOutput: "2000-01-02T20:34:56.123Z",
+input: time.Date(2000, time.January, 2, 20, 34, 56, .123456e9, time.UTC),
+},
 }
 
 for name, c := range cases {