#90 - Emit inserted object through SimpleR2dbcRepository.save(…) with given Id.

SimpleR2dbcRepository.save(…) now falls back to the saved object as emitted result if the INSERT statement does not return generated keys.

Adding H2 database engine for tests to simulate such behavior.

Original pull request: #90.

src/main/java/org/springframework/data/r2dbc/repository/support/SimpleR2dbcRepository.java

@@ -75,7 +75,8 @@ public class SimpleR2dbcRepository<T, ID> implements ReactiveCrudRepository<T, I
 					.into(entity.getJavaType()) //
 					.using(objectToSave) //
 					.map(converter.populateIdIfNecessary(objectToSave)) //
-					.one();
+					.first() //
+					.defaultIfEmpty(objectToSave);
 		}
 
 		Object id = entity.getRequiredId(objectToSave);