DATACMNS-1243 - Add converters from LocalDateTime to Instant and back.

This allows usage of Instant for AuditAware.

Original pull request: #268.

src/main/java/org/springframework/data/convert/Jsr310Converters.java

@@ -26,6 +26,7 @@ import java.time.LocalDateTime;
 import java.time.LocalTime;
 import java.time.Period;
 import java.time.ZoneId;
+import java.time.ZoneOffset;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -70,6 +71,8 @@ public abstract class Jsr310Converters {
 		converters.add(LocalTimeToDateConverter.INSTANCE);
 		converters.add(DateToInstantConverter.INSTANCE);
 		converters.add(InstantToDateConverter.INSTANCE);
+		converters.add(LocalDateTimeToInstantConverter.INSTANCE);
+		converters.add(InstantToLocalDateTimeConverter.INSTANCE);
 		converters.add(ZoneIdToStringConverter.INSTANCE);
 		converters.add(StringToZoneIdConverter.INSTANCE);
 		converters.add(DurationToStringConverter.INSTANCE);
@@ -178,6 +181,28 @@ public abstract class Jsr310Converters {
 		}
 	}
 
+	public static enum LocalDateTimeToInstantConverter implements Converter<LocalDateTime, Instant> {
+
+		INSTANCE;
+
+		@Nonnull
+		@Override
+		public Instant convert(LocalDateTime source) {
+			return source.atZone(systemDefault()).toInstant();
+		}
+	}
+
+	public static enum InstantToLocalDateTimeConverter implements Converter<Instant, LocalDateTime> {
+
+		INSTANCE;
+
+		@Nonnull
+		@Override
+		public LocalDateTime convert(Instant source) {
+			return LocalDateTime.ofInstant(source, systemDefault());
+		}
+	}
+
 	@WritingConverter
 	public static enum ZoneIdToStringConverter implements Converter<ZoneId, String> {
 

src/test/java/org/springframework/data/convert/Jsr310ConvertersUnitTests.java

@@ -145,6 +145,17 @@ public class Jsr310ConvertersUnitTests {
 			}
 		}
 
+		@Test // DATACMNS-1243
+		public void convertsLocalDateTimeToInstantAndBack() {
+
+			LocalDateTime dateTime = LocalDateTime.now();
+
+			Instant instant = CONVERSION_SERVICE.convert(dateTime, Instant.class);
+			LocalDateTime convertedDateTime = CONVERSION_SERVICE.convert(dateTime, LocalDateTime.class);
+
+			assertThat(convertedDateTime).isEqualTo(dateTime);
+		}
+
 		private static Predicate<Date> formatted(Temporal expected, String format) {
 
 			DateTimeFormatter formatter = DateTimeFormatter.ofPattern(format);