ScrollUtils must not modify source query when creating scroll filter.

This commit makes sure to create a new filter query object if needed instead of modifying the source query.
In doing so we retain the original source and prevent errors when attempting to alter immutable sources.

Closes #5159
Original pull request: #5160

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ScrollUtils.java

@@ -29,6 +29,7 @@ import org.springframework.data.domain.ScrollPosition.Direction;
 import org.springframework.data.domain.Window;
 import org.springframework.data.mongodb.core.EntityOperations.Entity;
 import org.springframework.data.mongodb.core.query.Query;
+import org.springframework.lang.CheckReturnValue;
 import org.springframework.util.Assert;
 
 /**
@@ -49,7 +50,6 @@ class ScrollUtils {
 	 */
 	static KeysetScrollQuery createKeysetPaginationQuery(Query query, String idPropertyName) {
 
-
 		KeysetScrollPosition keyset = query.getKeyset();
 
 		Assert.notNull(keyset, "Query.keyset must not be null");
@@ -145,6 +145,7 @@ class ScrollUtils {
 			return fieldsObject;
 		}
 
+		@CheckReturnValue
 		public Document createQuery(KeysetScrollPosition keyset, Document queryObject, Document sortObject) {
 
 			Map<String, Object> keysetValues = keyset.getKeys();
@@ -189,11 +190,13 @@ class ScrollUtils {
 				}
 			}
 
-			if (!or.isEmpty()) {
-				queryObject.put("$or", or);
+			if (or.isEmpty()) {
+				return queryObject;
 			}
 
-			return queryObject;
+			Document filterQuery = new Document(queryObject);
+			filterQuery.put("$or", or);
+			return filterQuery;
 		}
 
 		protected String getComparator(int sortOrder) {

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/AbstractPersonRepositoryIntegrationTests.java

@@ -232,6 +232,19 @@ public abstract class AbstractPersonRepositoryIntegrationTests implements Dirtie
 		assertThat(page).contains(carter);
 	}
 
+	@Test // GH-5159
+	void allowsToScrollThroughEntriesWithoutAnyCriteria() {
+
+		Window<Person> page = repository.findAllBy(Limit.of(2), ScrollPosition.keyset());
+		assertThat(page.isLast()).isFalse();
+
+		while (!page.isLast()) {
+
+			assertThat(page.size()).isEqualTo(2);
+			page = repository.findAllBy(Limit.of(2), page.positionAt(1));
+		}
+	}
+
 	@Test // GH-4397
 	void appliesLimitToScrollingCorrectly() {
 

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/PersonRepository.java

@@ -126,6 +126,15 @@ public interface PersonRepository extends MongoRepository<Person, String>, Query
 	@Query("{'age' : { '$lt' : ?0 } }")
 	List<Person> findByAgeLessThan(int age, Sort sort);
 
+	/**
+	 * Returns a scroll of all {@link Person}s in natural order.
+	 *
+	 * @param limit window size
+	 * @param scrollPosition scroll position start from
+	 * @return
+	 */
+	Window<Person> findAllBy(Limit limit, ScrollPosition scrollPosition);
+
 	/**
 	 * Returns a scroll of {@link Person}s with a lastname matching the given one (*-wildcards supported).
 	 *