Retain scroll direction in Keyset position function of the correct item.

Closes #2999

Author: mp911de

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/ScrollDelegate.java

@@ -80,14 +80,14 @@ private static <T> Window<T> createWindow(Sort sort, int limit, Direction direct
 			JpaEntityInformation<T, ?> entity, List<T> result) {
 
 		KeysetScrollDelegate delegate = KeysetScrollDelegate.of(direction);
-		List<T> resultsToUse = delegate.postProcessResults(result);
+		List<T> resultsToUse = delegate.getResultWindow(delegate.postProcessResults(result), limit);
 
 		IntFunction<ScrollPosition> positionFunction = value -> {
 
-			T object = result.get(value);
+			T object = resultsToUse.get(value);
 			Map<String, Object> keys = entity.getKeyset(sort.stream().map(Order::getProperty).toList(), object);
 
-			return ScrollPosition.forward(keys);
+			return ScrollPosition.of(keys, direction);
 		};
 
 		return Window.from(delegate.getResultWindow(resultsToUse, limit), positionFunction, hasMoreElements(result, limit));

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java

@@ -60,6 +60,7 @@
 import org.springframework.data.domain.ExampleMatcher.StringMatcher;
 import org.springframework.data.domain.Sort.Direction;
 import org.springframework.data.domain.Sort.Order;
+import org.springframework.data.domain.ExampleMatcher.*;
 import org.springframework.data.jpa.domain.Specification;
 import org.springframework.data.jpa.domain.sample.Address;
 import org.springframework.data.jpa.domain.sample.QUser;
@@ -1308,6 +1309,31 @@ void scrollByExampleKeysetBackward() {
 		assertThat(previousWindow.hasNext()).isTrue();
 	}
 
+	@Test // GH-2999
+	void scrollInitiallyByExampleKeysetBackward() {
+
+		User jane1 = new User("Jane", "Doe", "[email protected]");
+		User jane2 = new User("Jane", "Doe", "[email protected]");
+		User john1 = new User("John", "Doe", "[email protected]");
+		User john2 = new User("John", "Doe", "[email protected]");
+
+		repository.saveAllAndFlush(Arrays.asList(john1, john2, jane1, jane2));
+
+		Example<User> example = Example.of(new User("J", null, null),
+				matching().withMatcher("firstname", GenericPropertyMatcher::startsWith).withIgnorePaths("age", "createdAt",
+						"dateOfBirth"));
+
+		Window<User> firstWindow = repository.findBy(example,
+				q -> q.limit(2).sortBy(Sort.by("firstname", "emailAddress")).scroll(ScrollPosition.keyset().backward()));
+
+		assertThat(firstWindow).containsExactly(john1, john2);
+
+		Window<User> previousWindow = repository.findBy(example,
+				q -> q.limit(2).sortBy(Sort.by("firstname", "emailAddress")).scroll(firstWindow.positionAt(0)));
+
+		assertThat(previousWindow).containsExactly(jane1, jane2);
+	}
+
 	@Test // GH-2878
 	void scrollByPredicateOffset() {