Reestablish previous exception behavior.

When saving an Aggregate which is not new, but has a null version attribute we now throw a DbActionExecutionException, like we used to.

Closes #1254

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/JdbcAggregateTemplate.java

@@ -415,9 +415,7 @@ public class JdbcAggregateTemplate implements JdbcAggregateOperations {
 			// If the root aggregate has a version property, increment it.
 			previousVersion = RelationalEntityVersionUtils.getVersionNumberFromEntity(instance, persistentEntity, converter);
 
-			Assert.notNull(previousVersion, "The root aggregate cannot be updated because the version property is null.");
-
-			long newVersion = previousVersion.longValue() + 1;
+			long newVersion = (previousVersion == null ? 0 : previousVersion.longValue()) + 1;
 
 			preparedInstance = RelationalEntityVersionUtils.setVersionNumberOnEntity(instance, newVersion, persistentEntity,
 					converter);

spring-data-jdbc/src/test/java/org/springframework/data/jdbc/core/JdbcAggregateTemplateIntegrationTests.java

@@ -54,6 +54,7 @@ import org.springframework.data.annotation.PersistenceConstructor;
 import org.springframework.data.annotation.ReadOnlyProperty;
 import org.springframework.data.annotation.Version;
 import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.Persistable;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.jdbc.core.convert.DataAccessStrategy;
 import org.springframework.data.jdbc.core.convert.JdbcConverter;
@@ -278,7 +279,8 @@ class JdbcAggregateTemplateIntegrationTests {
 		template.save(createLegoSet("Star"));
 		template.save(createLegoSet("Frozen"));
 
-		final Sort sort = Sort.by(new Sort.Order(Sort.Direction.ASC, "name", Sort.NullHandling.NULLS_LAST));
+		final Sort sort =
+				Sort.by(new Sort.Order(Sort.Direction.ASC, "name", Sort.NullHandling.NULLS_LAST));
 		Iterable<LegoSet> reloadedLegoSets = template.findAll(LegoSet.class, sort);
 
 		assertThat(reloadedLegoSets) //
@@ -923,6 +925,16 @@ class JdbcAggregateTemplateIntegrationTests {
 		saveAndUpdateAggregateWithPrimitiveVersion(new AggregateWithPrimitiveShortVersion(), Number::shortValue);
 	}
 
+	@Test // GH-1254
+	void saveAndUpdateAggregateWithIdAndNullVersion() {
+
+		PersistableVersionedAggregate aggregate = new PersistableVersionedAggregate();
+		aggregate.setVersion(null);
+		aggregate.setId(23L);
+
+		assertThatThrownBy(() -> template.save(aggregate)).isInstanceOf(DbActionExecutionException.class);
+	}
+
 	@Test // DATAJDBC-462
 	@EnabledOnFeature(SUPPORTS_QUOTED_IDS)
 	void resavingAnUnversionedEntity() {
@@ -1115,18 +1127,15 @@ class JdbcAggregateTemplateIntegrationTests {
 
 		@Column("id4") @Id private Long id;
 		String name;
-		@MappedCollection(idColumn = "LIST_PARENT")
-		List<ElementNoId> content = new ArrayList<>();
+		@MappedCollection(idColumn = "LIST_PARENT") List<ElementNoId> content = new ArrayList<>();
 	}
 
 	@Table("LIST_PARENT")
 	static class ListParentAllArgs {
 
-		@Column("id4") @Id
-		private final Long id;
+		@Column("id4") @Id private final Long id;
 		private final String name;
-		@MappedCollection(idColumn = "LIST_PARENT")
-		private final List<ElementNoId> content = new ArrayList<>();
+		@MappedCollection(idColumn = "LIST_PARENT") private final List<ElementNoId> content = new ArrayList<>();
 
 		@PersistenceConstructor
 		ListParentAllArgs(Long id, String name, List<ElementNoId> content) {
@@ -1287,6 +1296,20 @@ class JdbcAggregateTemplateIntegrationTests {
 		abstract void setVersion(Number newVersion);
 	}
 
+	@Data
+	@Table("VERSIONED_AGGREGATE")
+	static class PersistableVersionedAggregate implements Persistable<Long> {
+
+		@Id private Long id;
+
+		@Version Long version;
+
+		@Override
+		public boolean isNew() {
+			return getId() == null;
+		}
+	}
+
 	@Value
 	@With
 	@Table("VERSIONED_AGGREGATE")