Ensure joda compatibility in custom date formats (#38171)

If custom date formats are used, there may be combinations that the new
performat DateFormatters.from() method has not covered yet. This adds a
few such corner cases and ensures the tests are correctly commented
out.

Author: spinscale

server/src/main/java/org/elasticsearch/common/time/DateFormatters.java

@@ -1604,13 +1604,16 @@ public static ZonedDateTime from(TemporalAccessor accessor) {
         } else if (isLocalDateSet) {
             return localDate.atStartOfDay(zoneId);
         } else if (isLocalTimeSet) {
-            return of(LOCALDATE_EPOCH, localTime, zoneId);
+            return of(getLocaldate(accessor), localTime, zoneId);
         } else if (accessor.isSupported(ChronoField.YEAR)) {
             if (accessor.isSupported(MONTH_OF_YEAR)) {
                 return getFirstOfMonth(accessor).atStartOfDay(zoneId);
             } else {
                 return Year.of(accessor.get(ChronoField.YEAR)).atDay(1).atStartOfDay(zoneId);
             }
+        } else if (accessor.isSupported(MONTH_OF_YEAR)) {
+            // missing year, falling back to the epoch and then filling
+            return getLocaldate(accessor).atStartOfDay(zoneId);
         } else if (accessor.isSupported(WeekFields.ISO.weekBasedYear())) {
             if (accessor.isSupported(WeekFields.ISO.weekOfWeekBasedYear())) {
                 return Year.of(accessor.get(WeekFields.ISO.weekBasedYear()))
@@ -1630,6 +1633,18 @@ public static ZonedDateTime from(TemporalAccessor accessor) {
         throw new IllegalArgumentException("temporal accessor [" + accessor + "] cannot be converted to zoned date time");
     }
 
+    private static LocalDate getLocaldate(TemporalAccessor accessor) {
+        if (accessor.isSupported(MONTH_OF_YEAR)) {
+            if (accessor.isSupported(DAY_OF_MONTH)) {
+                return LocalDate.of(1970, accessor.get(MONTH_OF_YEAR), accessor.get(DAY_OF_MONTH));
+            } else {
+                return LocalDate.of(1970, accessor.get(MONTH_OF_YEAR), 1);
+            }
+        }
+
+        return LOCALDATE_EPOCH;
+    }
+
     @SuppressForbidden(reason = "ZonedDateTime.of is fine here")
     private static ZonedDateTime of(LocalDate localDate, LocalTime localTime, ZoneId zoneId) {
         return ZonedDateTime.of(localDate, localTime, zoneId);

server/src/test/java/org/elasticsearch/common/joda/JavaJodaTimeDuellingTests.java

@@ -62,11 +62,14 @@ public void testTimeZoneFormatting() {
         formatter3.parse("20181126T121212.123-0830");
     }
 
+    public void testCustomTimeFormats() {
+        assertSameDate("2010 12 06 11:05:15", "yyyy dd MM HH:mm:ss");
+        assertSameDate("12/06", "dd/MM");
+        assertSameDate("Nov 24 01:29:01 -0800", "MMM dd HH:mm:ss Z");
+    }
+
     // this test requires tests to run with -Djava.locale.providers=COMPAT in order to work
-//    public void testCustomTimeFormats() {
-//        assertSameDate("2010 12 06 11:05:15", "yyyy dd MM HH:mm:ss");
-//        assertSameDate("12/06", "dd/MM");
-//        assertSameDate("Nov 24 01:29:01 -0800", "MMM dd HH:mm:ss Z");
+//    public void testCustomLocales() {
 //
 //        // also ensure that locale based dates are the same
 //        assertSameDate("Di., 05 Dez. 2000 02:55:00 -0800", "E, d MMM yyyy HH:mm:ss Z", LocaleUtils.parse("de"));