Introduce ManagedTypes.

We now provide an abstraction to describe a collection of entity types that can be provided to the mapping context as improvement over `Set<Class>` for easier context setup.

Original pull request: #2635.
Closes #2634.

src/test/java/org/springframework/data/classloadersupport/HidingClassLoader.java

@@ -34,6 +34,7 @@ import org.springframework.util.Assert;
  *
  * @author Jens Schauder
  * @author Oliver Gierke
+ * @author Christoph Strobl
  */
 public class HidingClassLoader extends ShadowingClassLoader {
 
@@ -61,11 +62,21 @@ public class HidingClassLoader extends ShadowingClassLoader {
 				.collect(Collectors.toList()));
 	}
 
+	public static HidingClassLoader hideTypes(Class<?>... types) {
+
+		Assert.notNull(types, "Types must not be null!");
+
+		return new HidingClassLoader(Arrays.stream(types)//
+				.map(it -> it.getName())//
+				.collect(Collectors.toList()));
+	}
+
 	@Override
 	public Class<?> loadClass(String name) throws ClassNotFoundException {
 
-		checkIfHidden(name);
-		return super.loadClass(name);
+		Class<?> loaded = super.loadClass(name);
+		checkIfHidden(loaded);
+		return loaded;
 	}
 
 	@Override
@@ -76,13 +87,14 @@ public class HidingClassLoader extends ShadowingClassLoader {
 	@Override
 	protected Class<?> findClass(String name) throws ClassNotFoundException {
 
-		checkIfHidden(name);
-		return super.findClass(name);
+		Class<?> loaded = super.findClass(name);
+		checkIfHidden(loaded);
+		return loaded;
 	}
 
-	private void checkIfHidden(String name) throws ClassNotFoundException {
+	private void checkIfHidden(Class<?> type) throws ClassNotFoundException {
 
-		if (hidden.stream().anyMatch(it -> name.startsWith(it))) {
+		if (hidden.stream().anyMatch(it -> type.getName().startsWith(it))) {
 			throw new ClassNotFoundException();
 		}
 	}

src/test/java/org/springframework/data/domain/ManagedTypesUnitTests.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2022 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.domain;
+
+import static org.assertj.core.api.Assertions.*;
+import static org.mockito.ArgumentMatchers.*;
+import static org.mockito.Mockito.*;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+/**
+ * @author Christoph Strobl
+ */
+@ExtendWith(MockitoExtension.class)
+class ManagedTypesUnitTests {
+
+	@Mock Consumer<Class<?>> action;
+
+	@Test // GH-2634
+	void emptyNeverCallsAction() {
+
+		ManagedTypes.empty().forEach(action);
+		verify(action, never()).accept(any());
+	}
+
+	@Test // GH-2634
+	void supplierBasedManagedTypesAreEvaluatedLazily() {
+
+		Supplier<Iterable<Class<?>>> typesSupplier = spy(new Supplier<Iterable<Class<?>>>() {
+			@Override
+			public Iterable<Class<?>> get() {
+				return Collections.singleton(Object.class);
+			}
+		});
+
+		ManagedTypes managedTypes = ManagedTypes.fromSupplier(typesSupplier);
+
+		managedTypes.forEach(action); // 1st invocation
+		verify(action).accept(any());
+		verify(typesSupplier).get();
+
+		managedTypes.forEach(action); // 2nd invocation
+		verify(action, times(2)).accept(any());
+		verify(typesSupplier, times(1)).get();
+	}
+
+	@Test // GH-2634
+	void toListOnEmptyReturnsEmptyList() {
+		assertThat(ManagedTypes.empty().toList()).isEmpty();
+	}
+
+	@Test // GH-2634
+	void toListContainsEntriesInOrder() {
+		assertThat(ManagedTypes.fromIterable(Arrays.asList(Object.class, List.class)).toList()).containsExactly(Object.class,
+				List.class);
+	}
+}

src/test/java/org/springframework/data/repository/config/RepositoryBeanDefinitionRegistrarSupportUnitTests.java

@@ -187,7 +187,7 @@ class RepositoryBeanDefinitionRegistrarSupportUnitTests {
 		}
 
 		@Override
-		protected String getModulePrefix() {
+		public String getModulePrefix() {
 			return "commons";
 		}
 	}

src/test/java/org/springframework/data/repository/config/RepositoryConfigurationDelegateUnitTests.java

@@ -24,7 +24,6 @@ import org.mockito.Mockito;
 import org.mockito.junit.jupiter.MockitoExtension;
 import org.mockito.junit.jupiter.MockitoSettings;
 import org.mockito.quality.Strictness;
-
 import org.springframework.aop.framework.Advised;
 import org.springframework.beans.factory.ListableBeanFactory;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;

src/test/java/org/springframework/data/repository/config/RepositoryConfigurationExtensionSupportUnitTests.java

@@ -100,7 +100,7 @@ class RepositoryConfigurationExtensionSupportUnitTests {
 	static class SampleRepositoryConfigurationExtension extends RepositoryConfigurationExtensionSupport {
 
 		@Override
-		protected String getModulePrefix() {
+		public String getModulePrefix() {
 			return "core";
 		}
 
@@ -123,7 +123,7 @@ class RepositoryConfigurationExtensionSupportUnitTests {
 	static class NonIdentifyingConfigurationExtension extends RepositoryConfigurationExtensionSupport {
 
 		@Override
-		protected String getModulePrefix() {
+		public String getModulePrefix() {
 			return "non-identifying";
 		}