Disable tests on Java 16 that require class-based proxies.

Original pull request: #3687.
Resolves #3656

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

@@ -71,7 +71,7 @@ public class MongoMappingContext extends AbstractMappingContext<MongoPersistentE
 	@Override
 	protected boolean shouldCreatePersistentEntityFor(TypeInformation<?> type) {
 
-		if(NullableWrapperConverters.supports(type.getType())) {
+		if (NullableWrapperConverters.supports(type.getType())) {
 			return false;
 		}
 
@@ -139,7 +139,7 @@ public class MongoMappingContext extends AbstractMappingContext<MongoPersistentE
 
 		MongoPersistentEntity<?> entity = super.getPersistentEntity(persistentProperty);
 
-		if(entity == null || !persistentProperty.isUnwrapped()) {
+		if (entity == null || !persistentProperty.isUnwrapped()) {
 			return entity;
 		}
 

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/DbRefMappingMongoConverterUnitTests.java

@@ -36,6 +36,8 @@ import org.bson.conversions.Bson;
 import org.bson.types.ObjectId;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.DisabledForJreRange;
+import org.junit.jupiter.api.condition.JRE;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.Mock;
 import org.mockito.Mockito;
@@ -181,6 +183,7 @@ class DbRefMappingMongoConverterUnitTests {
 	}
 
 	@Test // DATAMONGO-348
+	@DisabledForJreRange(min = JRE.JAVA_16, disabledReason = "Class Proxies for eg. ArrayList require to open java.util.")
 	void lazyLoadingProxyForLazyDbRefOnConcreteCollection() {
 
 		String id = "42";
@@ -508,6 +511,7 @@ class DbRefMappingMongoConverterUnitTests {
 	}
 
 	@Test // DATAMONGO-1076
+	@DisabledForJreRange(min = JRE.JAVA_16, disabledReason = "Class Proxies for eg. ArrayList require to open java.util.")
 	void shouldNotTriggerResolvingOfLazyLoadedProxyWhenFinalizeMethodIsInvoked() throws Exception {
 
 		MongoPersistentEntity<?> entity = mappingContext
@@ -526,6 +530,7 @@ class DbRefMappingMongoConverterUnitTests {
 	}
 
 	@Test // DATAMONGO-1194
+	@DisabledForJreRange(min = JRE.JAVA_16, disabledReason = "Class Proxies for eg. ArrayList require to open java.util.")
 	void shouldBulkFetchListOfReferences() {
 
 		String id1 = "1";
@@ -576,6 +581,7 @@ class DbRefMappingMongoConverterUnitTests {
 	}
 
 	@Test // DATAMONGO-1194
+	@DisabledForJreRange(min = JRE.JAVA_16, disabledReason = "Class Proxies for eg. ArrayList require to open java.util.")
 	void shouldFallbackToOneByOneFetchingWhenElementsInListOfReferencesPointToDifferentCollections() {
 
 		String id1 = "1";

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

@@ -22,14 +22,15 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
-import org.junit.Before;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.DisabledForJreRange;
+import org.junit.jupiter.api.condition.JRE;
+import org.junit.jupiter.api.extension.ExtendWith;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.data.mongodb.core.MongoOperations;
 import org.springframework.test.context.ContextConfiguration;
-import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.test.context.junit.jupiter.SpringExtension;
 
 /**
  * Integration test for {@link PersonRepository} for lazy loading support.
@@ -38,13 +39,13 @@ import org.springframework.test.context.junit4.SpringRunner;
  * @author Oliver Gierke
  */
 @ContextConfiguration(locations = "PersonRepositoryIntegrationTests-context.xml")
-@RunWith(SpringRunner.class)
+@ExtendWith(SpringExtension.class)
 public class PersonRepositoryLazyLoadingIntegrationTests {
 
 	@Autowired PersonRepository repository;
 	@Autowired MongoOperations operations;
 
-	@Before
+	@BeforeEach
 	public void setUp() throws InterruptedException {
 
 		repository.deleteAll();
@@ -61,7 +62,6 @@ public class PersonRepositoryLazyLoadingIntegrationTests {
 		Person person = new Person();
 		person.setFirstname("Oliver");
 		person.setFans(Arrays.asList(thomas));
-		person.setRealFans(new ArrayList<User>(Arrays.asList(thomas)));
 		repository.save(person);
 
 		Person oliver = repository.findById(person.id).get();
@@ -75,7 +75,8 @@ public class PersonRepositoryLazyLoadingIntegrationTests {
 	}
 
 	@Test // DATAMONGO-348
-	public void shouldLoadAssociationWithDbRefOnConcreteCollectionAndLazyLoadingEnabled() throws Exception {
+	@DisabledForJreRange(min = JRE.JAVA_16, disabledReason = "Class Proxies for eg. ArrayList require to open java.util.")
+	public void shouldLoadAssociationWithDbRefOnConcreteCollectionAndLazyLoadingEnabled() {
 
 		User thomas = new User();
 		thomas.username = "Thomas";
@@ -83,7 +84,6 @@ public class PersonRepositoryLazyLoadingIntegrationTests {
 
 		Person person = new Person();
 		person.setFirstname("Oliver");
-		person.setFans(Arrays.asList(thomas));
 		person.setRealFans(new ArrayList<User>(Arrays.asList(thomas)));
 		repository.save(person);
 

src/main/asciidoc/reference/document-references.adoc

@@ -49,6 +49,9 @@ TIP: Lazily loaded ``DBRef``s can be hard to debug.
 Make sure tooling does not accidentally trigger proxy resolution by e.g. calling `toString()` or some inline debug rendering invoking property getters.
 Please consider to enable _trace_ logging for `org.springframework.data.mongodb.core.convert.DefaultDbRefResolver` to gain insight on `DBRef` resolution.
 
+CAUTION: Lazy loading may require class proxies, that in turn, might need access to jdk internals, that are not open, starting with Java 16+, due to https://openjdk.java.net/jeps/396[JEP 396: Strongly Encapsulate JDK Internals by Default].
+For those cases please consider falling back to an interface type (eg. switch from `ArrayList` to `List`) or provide the required `--add-opens` argument.
+
 [[mapping-usage.document-references]]
 === Using Document References
 
@@ -136,6 +139,9 @@ Result order of `Collection` like properties is restored based on the used looku
 | Resolves properties eagerly by default.
 |===
 
+CAUTION: Lazy loading may require class proxies, that in turn, might need access to jdk internals, that are not open, starting with Java 16+, due to https://openjdk.java.net/jeps/396[JEP 396: Strongly Encapsulate JDK Internals by Default].
+For those cases please consider falling back to an interface type (eg. switch from `ArrayList` to `List`) or provide the required `--add-opens` argument.
+
 `@DocumentReference(lookup)` allows defining filter queries that can be different from the `_id` field and therefore offer a flexible way of defining references between entities as demonstrated in the sample below, where the `Publisher` of a book is referenced by its acronym instead of the internal `id`.
 
 ====