fix(fcm): Fix issues in event_time timestamp parsing (#338)

* fix issues in event_time timestamp conversion

* fix the formatting issue in event_time timestamp

Author: chong-shao

src/main/java/com/google/firebase/messaging/AndroidNotification.java

@@ -28,6 +28,7 @@
 import java.util.Date;
 import java.util.List;
 import java.util.Map;
+import java.util.TimeZone;
 import java.util.concurrent.TimeUnit;
 
 /**
@@ -456,8 +457,9 @@ public Builder setSticky(boolean sticky) {
      * @return This builder.
      */
     public Builder setEventTimeInMillis(long eventTimeInMillis) {
-      this.eventTime = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSSSSSSS'Z'")
-          .format(new Date(eventTimeInMillis));
+      SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS000000'Z'");
+      dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
+      this.eventTime = dateFormat.format(new Date(eventTimeInMillis));
       return this;
     }
 

src/test/java/com/google/firebase/messaging/MessageTest.java

@@ -859,15 +859,13 @@ public void testExtendedAndroidNotificationParameters() throws IOException {
         .put("title", "title")
         .put("body", "body")
         .build();
-    String eventTime = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSSSSSSS'Z'", Locale.US)
-        .format(new Date(1546304523123L));
     Map<String, Object> androidConfig = ImmutableMap.<String, Object>builder()
         .put("notification", ImmutableMap.<String, Object>builder()
             .put("title", "android-title")
             .put("body", "android-body")
             .put("ticker", "ticker")
             .put("sticky", true)
-            .put("event_time", eventTime)
+            .put("event_time", "2019-01-01T01:02:03.123000000Z")
             .put("local_only", true)
             .put("notification_priority", "PRIORITY_HIGH")
             .put("vibrate_timings", ImmutableList.of("1s", "1.001000000s"))