Fix milliseconds bug in DateTime parseRfc3339. The fraction after the dot is not always 3

digits, in which case it must be multiplied by 10^n to get the correct
milliseconds.

Example1: 12:34.56 should have milliseconds=560, but it was returning only 56.

Example2: 12:34.56789 should have milliseconds=567, but it was returning 56789.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=104921033

Author: emrekultursay

google-http-client/src/main/java/com/google/api/client/util/DateTime.java

@@ -313,6 +313,9 @@ public static DateTime parseRfc3339(String str) throws NumberFormatException {
       second = Integer.parseInt(matcher.group(7)); // ss
       if (matcher.group(8) != null) { // contains .milliseconds?
         milliseconds = Integer.parseInt(matcher.group(8).substring(1)); // milliseconds
+        // The number of digits after the dot may not be 3. Need to renormalize.
+        int fractionDigits = matcher.group(8).substring(1).length() - 3;
+        milliseconds = (int) ((float) milliseconds / Math.pow(10, fractionDigits));
       }
     }
     Calendar dateTime = new GregorianCalendar(GMT);

google-http-client/src/test/java/com/google/api/client/util/DateTimeTest.java

@@ -120,7 +120,7 @@ public void testParseRfc3339() {
     assertEquals(0, value.getValue() % 100);
     value = DateTime.parseRfc3339("1997-01-01T12:00:27.87+00:20");
     assertFalse(value.isDateOnly());
-    assertEquals(87, value.getValue() % 1000); // check milliseconds
+    assertEquals(870, value.getValue() % 1000); // check milliseconds
 
     value = new DateTime("2007-06-01");
     assertTrue(value.isDateOnly());
@@ -138,6 +138,22 @@ public void testParseRfc3339() {
         DateTime.parseRfc3339("2007-06-01t22:50:00Z").getValue()); // from Section 4.2 Local Offsets
   }
 
+  public void testParseAndFormatRfc3339() {
+    // .12 becomes .120
+    String input = "1996-12-19T16:39:57.12-08:00";
+    String expected = "1996-12-19T16:39:57.120-08:00";
+    DateTime dt = DateTime.parseRfc3339(input);
+    String output = dt.toStringRfc3339();
+    assertEquals(expected, output);
+
+    // Truncated to milliseconds.
+    input    = "1996-12-19T16:39:57.123456789-08:00";
+    expected = "1996-12-19T16:39:57.123-08:00";
+    dt = DateTime.parseRfc3339(input);
+    output = dt.toStringRfc3339();
+    assertEquals(expected, output);
+  }
+
   private void expectExceptionForParseRfc3339(String input) {
     try {
       DateTime.parseRfc3339(input);