Refactor WritingContext#insertAll to use Collectors.partitioningBy instead of managing the partitions manually.

Author: ctailor2

spring-data-relational/src/main/java/org/springframework/data/relational/core/conversion/WritingContext.java

@@ -47,7 +47,7 @@ class WritingContext {
 	private final PersistentPropertyPaths<?, RelationalPersistentProperty> paths;
 	private final Map<PathNode, DbAction<?>> previousActions = new HashMap<>();
 	private final Map<PersistentPropertyPath<RelationalPersistentProperty>, List<PathNode>> nodesCache = new HashMap<>();
-	private boolean rootIncludeId;
+	private final boolean rootIncludeId;
 
 	WritingContext(RelationalMappingContext context, Object root, MutableAggregateChange<?> aggregateChange) {
 
@@ -126,9 +126,7 @@ private List<DbAction<?>> insertReferenced() {
 	private List<? extends DbAction<?>> insertAll(PersistentPropertyPath<RelationalPersistentProperty> path) {
 
 		RelationalPersistentEntity<?> persistentEntity = context.getRequiredPersistentEntity(path.getRequiredLeafProperty());
-		TreeMap<Boolean, List<DbAction.Insert<Object>>> insertsPartitionedByHasId = new TreeMap<>(BooleanComparator.TRUE_HIGH);
-		insertsPartitionedByHasId.put(true, new ArrayList<>());
-		insertsPartitionedByHasId.put(false, new ArrayList<>());
+		List<DbAction.Insert<Object>> inserts = new ArrayList<>();
 		from(path).forEach(node -> {
 
 			DbAction.WithEntity<?> parentAction = getAction(node.getParent());
@@ -150,11 +148,12 @@ private List<? extends DbAction<?>> insertAll(PersistentPropertyPath<RelationalP
 			}
 			boolean includeId = persistentEntity.getIdentifierAccessor(instance).getIdentifier() != null;
 			DbAction.Insert<Object> insert = new DbAction.Insert<>(instance, path, parentAction, qualifiers, includeId);
-			insertsPartitionedByHasId.get(includeId)
-					.add(insert);
+			inserts.add(insert);
 			previousActions.put(node, insert);
 		});
-		return insertsPartitionedByHasId.entrySet().stream()
+		return inserts.stream()
+				.collect(Collectors.partitioningBy(DbAction.Insert::isIncludeId))
+				.entrySet().stream()
 				.filter(entry -> (!entry.getValue().isEmpty()))
 				.map(entry -> {
 					List<DbAction.Insert<Object>> batch = entry.getValue();