DATAREDIS-1001 - Fix java.util.Date hash mapping when flattening out entries.

The AsArrayTypeDeserializer causes date values to be rendered as an array like [java.util.Date, 1561543964015] an therefore is 1. skipped when flattening and 2. if not skipped cannot be read back.
We now register an error handler along with a custom deserializer aware of the used date format to write and read date values without having to store an array but just the date msec.

Original pull request: #467.

src/test/java/org/springframework/data/redis/mapping/Jackson2HashMapperTests.java

@@ -97,5 +97,4 @@ public class Jackson2HashMapperTests {
 		Person result = (Person) mapper.fromHash(template.<String, Object> opsForHash().entries("JON-SNOW"));
 		Assert.assertThat(result, Is.is(jon));
 	}
-
 }

src/test/java/org/springframework/data/redis/mapping/Jackson2HashMapperUnitTests.java

@@ -20,6 +20,7 @@ import lombok.Data;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Date;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
@@ -161,6 +162,16 @@ public class Jackson2HashMapperUnitTests extends AbstractHashMapperTest {
 		assertBackAndForwardMapping(outer);
 	}
 
+	@Test // DATAREDIS-1001
+	public void dateValueShouldBeTreatedCorrectly() {
+
+		WithDate source = new WithDate();
+		source.string = "id-1";
+		source.date = new Date(1561543964015L);
+
+		assertBackAndForwardMapping(source);
+	}
+
 	@Data
 	public static class WithList {
 		List<String> strings;
@@ -174,4 +185,11 @@ public class Jackson2HashMapperUnitTests extends AbstractHashMapperTest {
 		Map<String, Object> objects;
 		Map<String, Person> persons;
 	}
+
+	@Data
+	static class WithDate {
+
+		private String string;
+		private Date date;
+	}
 }