Align OffsetScrolling to zero-based indexes.

Closes: #3409
Original pull request: #3415

Author: christophstrobl

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

@@ -259,8 +259,8 @@ public Query createQuery(JpaParametersParameterAccessor accessor) {
 		@SuppressWarnings("ConstantConditions")
 		private Query restrictMaxResultsIfNecessary(Query query, @Nullable ScrollPosition scrollPosition) {
 
-			if (scrollPosition instanceof OffsetScrollPosition offset) {
-				query.setFirstResult(Math.toIntExact(offset.getOffset()));
+			if (scrollPosition instanceof OffsetScrollPosition offset && !offset.isInitial()) {
+				query.setFirstResult(Math.toIntExact(offset.getOffset()) + 1);
 			}
 
 			if (tree.isLimiting()) {

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

@@ -71,7 +71,7 @@ public Window<T> scroll(Query query, Sort sort, ScrollPosition scrollPosition) {
 		}
 
 		if (scrollPosition instanceof OffsetScrollPosition offset) {
-			return createWindow(result, limit, OffsetScrollPosition.positionFunction(offset.getOffset()));
+			return createWindow(result, limit, OffsetScrollPosition.positionFunction(offset.isInitial() ? 0 : offset.getOffset()));
 		}
 
 		throw new UnsupportedOperationException("ScrollPosition " + scrollPosition + " not supported");

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/support/QuerydslJpaPredicateExecutor.java

@@ -196,7 +196,9 @@ public <S extends T, R> R findBy(Predicate predicate, Function<FetchableFluentQu
 			select = (AbstractJPAQuery<?, ?>) querydsl.applySorting(sort, select);
 
 			if (scrollPosition instanceof OffsetScrollPosition offset) {
-				select.offset(offset.getOffset());
+				if(!offset.isInitial()) {
+					select.offset(offset.getOffset() + 1);
+				}
 			}
 
 			return select.createQuery();

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/support/SimpleJpaRepository.java

@@ -512,7 +512,9 @@ private <S extends T, R> R doFindBy(Specification<T> spec, Class<T> domainClass,
 			TypedQuery<T> query = getQuery(specToUse, domainClass, sort);
 
 			if (scrollPosition instanceof OffsetScrollPosition offset) {
-				query.setFirstResult(Math.toIntExact(offset.getOffset()));
+				if(!offset.isInitial()) {
+					query.setFirstResult(Math.toIntExact(offset.getOffset()) + 1);
+				}
 			}
 
 			return query;

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

@@ -226,23 +226,34 @@ void executesQueryToSliceWithUnpaged() {
 		assertThat(slice.hasNext()).isFalse();
 	}
 
-	@Test // DATAJPA-94
+	@Test // GH-3077, GH-3409
 	void executesQueryWithLimitAndScrollPosition() {
 
 		Window<User> first = userRepository.findByLastnameOrderByFirstname(Limit.of(1), //
-				ScrollPosition.offset(), //
+				ScrollPosition.offset(), // initial position no offset
 				"Matthews" //
 		);
 
 		Window<User> next = userRepository.findByLastnameOrderByFirstname(Limit.of(1), //
-				ScrollPosition.offset(1), //
+				ScrollPosition.offset(0), // first position, offset = 1
 				"Matthews" //
 		);
 
 		assertThat(first).containsExactly(dave);
 		assertThat(next).containsExactly(oliver);
 	}
 
+	@Test // GH-3409
+	void executesWindowQueryWithPageable() {
+
+		Window<User> first = userRepository.findByLastnameOrderByFirstname("Matthews", PageRequest.of(0,1));
+
+		Window<User> next = userRepository.findByLastnameOrderByFirstname("Matthews", PageRequest.of(1,1));
+
+		assertThat(first).containsExactly(dave);
+		assertThat(next).containsExactly(oliver);
+	}
+
 	@Test // GH-3077
 	void shouldProjectWithKeysetScrolling() {
 

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

@@ -1430,7 +1430,7 @@ void scrollByPartTreeKeysetBackward() {
 		assertThat(previousWindow.hasNext()).isFalse();
 	}
 
-	@Test // GH-3015
+	@Test // GH-3015, GH-3407
 	void shouldApplyOffsetScrollPosition() {
 
 		User jane1 = new User("Jane", "Doe", "jane@doe1.com");
@@ -1441,7 +1441,7 @@ void shouldApplyOffsetScrollPosition() {
 		repository.saveAllAndFlush(Arrays.asList(john1, john2, jane1, jane2));
 
 		Window<User> atOffset3 = repository.findByFirstnameStartingWithOrderByFirstnameAscEmailAddressAsc("J",
-				ScrollPosition.offset(3));
+				ScrollPosition.offset(2));
 
 		assertThat(atOffset3).containsExactly(john2);
 	}

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

@@ -197,6 +197,8 @@ Window<User> findTop3ByFirstnameStartingWithOrderByFirstnameAscEmailAddressAsc(S
 
 	Window<User> findByLastnameOrderByFirstname(Limit limit, ScrollPosition scrollPosition, String lastname);
 
+	Window<User> findByLastnameOrderByFirstname(String lastname, Pageable page);
+
 	Window<NameOnly> findTop1ByLastnameOrderByFirstname(ScrollPosition scrollPosition, String lastname);
 
 	List<User> findByLastnameIgnoringCaseLike(String lastname);