DATAES-847 - Add missing DateFormat values.

Original PR: spring-projects#469

Author: timtebeek

src/main/java/org/springframework/data/elasticsearch/annotations/DateFormat.java

@@ -17,15 +17,16 @@
 
 /**
  * @author Jakub Vavrik
+ * @author Tim te Beek
  *         Values based on reference doc - https://www.elastic.co/guide/reference/mapping/date-format/
  */
 public enum DateFormat {
 	none, custom, basic_date, basic_date_time, basic_date_time_no_millis, basic_ordinal_date, basic_ordinal_date_time,
 	basic_ordinal_date_time_no_millis, basic_time, basic_time_no_millis, basic_t_time, basic_t_time_no_millis,
 	basic_week_date, basic_week_date_time, basic_week_date_time_no_millis, date, date_hour, date_hour_minute,
 	date_hour_minute_second, date_hour_minute_second_fraction, date_hour_minute_second_millis, date_optional_time,
-	date_time, date_time_no_millis, hour, hour_minute, hour_minute_second, hour_minute_second_fraction,
-	hour_minute_second_millis, ordinal_date, ordinal_date_time, ordinal_date_time_no_millis, time, time_no_millis,
-	t_time, t_time_no_millis, week_date, week_date_time, weekDateTimeNoMillis, week_year, weekyearWeek,
-	weekyearWeekDay, year, year_month, year_month_day
+	date_time, date_time_no_millis, epoch_millis, epoch_second, hour, hour_minute, hour_minute_second,
+	hour_minute_second_fraction, hour_minute_second_millis, ordinal_date, ordinal_date_time,
+	ordinal_date_time_no_millis, time, time_no_millis, t_time, t_time_no_millis, week_date, week_date_time,
+	week_date_time_no_millis, weekyear, weekyear_week, weekyear_week_day, year, year_month, year_month_day
 }

src/test/java/org/springframework/data/elasticsearch/core/convert/ElasticsearchDateConverterTests.java

@@ -2,6 +2,7 @@
 
 import static org.assertj.core.api.Assertions.*;
 
+import java.time.Instant;
 import java.time.LocalDate;
 import java.time.LocalDateTime;
 import java.time.ZoneId;
@@ -16,6 +17,7 @@
 
 /**
  * @author Peter-Josef Meisch
+ * @author Tim te Beek
  */
 class ElasticsearchDateConverterTests {
 
@@ -76,4 +78,24 @@ void shouldParseLegacyDateFromString() {
 
 		assertThat(parsed).isEqualTo(legacyDate);
 	}
+
+	@Test
+	void shouldParseEpochMillisString() {
+		Instant instant = Instant.ofEpochMilli(1234568901234L);
+		ElasticsearchDateConverter converter = ElasticsearchDateConverter.of(DateFormat.epoch_millis);
+
+		Date parsed = converter.parse("1234568901234");
+
+		assertThat(parsed.toInstant()).isEqualTo(instant);
+	}
+
+	@Test
+	void shouldConvertInstantToString() {
+		Instant instant = Instant.ofEpochMilli(1234568901234L);
+		ElasticsearchDateConverter converter = ElasticsearchDateConverter.of(DateFormat.epoch_millis);
+
+		String formatted = converter.format(instant);
+
+		assertThat(formatted).isEqualTo("1234568901234");
+	}
 }