DATAMONGO-1992 - Disable test for storing Optional properties.

Reading java.util.Optional is now no longer possible as we do not allow modifying immutable (final) fields.

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/MappingMongoConverterUnitTests.java

@@ -1694,6 +1694,7 @@ public class MappingMongoConverterUnitTests {
 	}
 
 	@Test // DATAMONGO-1128
+	@Ignore("Broken by DATAMONGO-1992 - In fact, storing Optional fields seems an anti-pattern.")
 	public void readsOptionalsCorrectly() {
 
 		LocalDateTime now = LocalDateTime.now();