HHH-18829 Test:

- Hibernate Processor - generate ID class in metadata class if entity not annotated with @IdClass;
          order of record components must match order of properties in entity class
    - Hibernate Core - check if ID class has been properly generated with preserved order of components
    - Annotated existing test entity classes with @Exclude when ID class can not be generated without causing compilation errors

hibernate-core/src/test/java/org/hibernate/orm/test/annotations/derivedidentities/bidirectional/Order.java

@@ -13,9 +13,11 @@ import jakarta.persistence.GeneratedValue;
 import jakarta.persistence.Id;
 import jakarta.persistence.OneToMany;
 import jakarta.persistence.Table;
+import org.hibernate.annotations.processing.Exclude;
 
 @SuppressWarnings("serial")
 @Entity
+@Exclude
 @Table(name = "orders")
 public class Order implements Serializable
 {

hibernate-core/src/test/java/org/hibernate/orm/test/annotations/derivedidentities/bidirectional/OrderLine.java

@@ -10,9 +10,11 @@ import jakarta.persistence.Id;
 import jakarta.persistence.JoinColumn;
 import jakarta.persistence.ManyToOne;
 import jakarta.persistence.Table;
+import org.hibernate.annotations.processing.Exclude;
 
 @SuppressWarnings("serial")
 @Entity
+@Exclude
 @Table(name = "order_line")
 // @IdClass(OrderLinePK.class)
 public class OrderLine implements Serializable

hibernate-core/src/test/java/org/hibernate/orm/test/annotations/derivedidentities/bidirectional/Product.java

@@ -9,9 +9,11 @@ import jakarta.persistence.Entity;
 import jakarta.persistence.GeneratedValue;
 import jakarta.persistence.Id;
 import jakarta.persistence.Table;
+import org.hibernate.annotations.processing.Exclude;
 
 @SuppressWarnings("serial")
 @Entity
+@Exclude
 @Table(name = "products")
 public class Product implements Serializable
 {

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/hhh18829/AutoGeneratedIdClassTest.java

@@ -0,0 +1,52 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.orm.test.mapping.hhh18829;
+
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.JiraKey;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import java.lang.reflect.InvocationTargetException;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+@DomainModel(annotatedClasses = EmployeeWithoutIdClass.class)
+@JiraKey(" HHH-18829")
+@SessionFactory
+public class AutoGeneratedIdClassTest {
+
+	@BeforeAll
+	void setUp(SessionFactoryScope sessionFactoryScope) {
+		sessionFactoryScope.inTransaction( sess -> {
+			final var one = new EmployeeWithoutIdClass();
+			one.empName = "John Doe";
+			one.empId = 1;
+			one.address = "10 Downing Street, SW1A 2AA";
+			sess.persist( one );
+
+			final var two = new EmployeeWithoutIdClass();
+			two.empName = "Dave Default";
+			two.empId = 1;
+			two.address = "1600 Pennsylvania Avenue";
+			sess.persist( two );
+		} );
+	}
+
+	@Test
+	public void test(SessionFactoryScope sessionFactoryScope)
+			throws ClassNotFoundException, InvocationTargetException, InstantiationException, IllegalAccessException {
+		final var idClass = Class.forName( EmployeeWithoutIdClass.class.getName() + "_$Id" );
+		final var id = idClass.getConstructors()[0].newInstance( "John Doe", 1 );
+		final var employees = sessionFactoryScope.fromSession(
+				sess -> sess.createQuery( "from EmployeeWithoutIdClass where id=:id", EmployeeWithoutIdClass.class ).setParameter( "id", id )
+						.getResultList()
+		);
+		assertEquals( 1, employees.size() );
+		assertEquals( "10 Downing Street, SW1A 2AA", employees.get( 0 ).address );
+	}
+}

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/hhh18829/EmployeeWithoutIdClass.java

@@ -0,0 +1,17 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.orm.test.mapping.hhh18829;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+
+@Entity
+public class EmployeeWithoutIdClass {
+	@Id
+	String empName;
+	@Id
+	Integer empId;
+	String address;
+}

tooling/metamodel-generator/src/test/java/org/hibernate/processor/test/hhh18829/Address.java

@@ -0,0 +1,12 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.processor.test.hhh18829;
+
+import jakarta.persistence.MappedSuperclass;
+
+@MappedSuperclass
+public class Address {
+	String address;
+}

tooling/metamodel-generator/src/test/java/org/hibernate/processor/test/hhh18829/AnotherEmployee.java

@@ -0,0 +1,33 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.processor.test.hhh18829;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+
+@Entity
+public class AnotherEmployee extends Address {
+	Integer empId;
+
+	String empName;
+
+	@Id
+	public Integer getEmpId() {
+		return empId;
+	}
+
+	public void setEmpId(Integer empId) {
+		this.empId = empId;
+	}
+
+	@Id
+	public String getEmpName() {
+		return empName;
+	}
+
+	public void setEmpName(String empName) {
+		this.empName = empName;
+	}
+}

tooling/metamodel-generator/src/test/java/org/hibernate/processor/test/hhh18829/AutoGeneratedIdClassTest.java

@@ -0,0 +1,53 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.processor.test.hhh18829;
+
+import org.hibernate.processor.test.util.CompilationTest;
+import org.hibernate.processor.test.util.TestForIssue;
+import org.hibernate.processor.test.util.TestUtil;
+import org.hibernate.processor.test.util.WithClasses;
+import org.junit.Test;
+
+import java.lang.reflect.RecordComponent;
+import java.util.Arrays;
+
+import static org.hibernate.processor.test.util.TestUtil.getMetamodelClassFor;
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+@TestForIssue(jiraKey = " HHH-18829")
+public class AutoGeneratedIdClassTest extends CompilationTest {
+
+	@Test
+	@WithClasses({Employee.class, AnotherEmployee.class, Address.class, EmployeeWithIdClass.class})
+	@TestForIssue(jiraKey = "HHH-18829")
+	public void test() {
+		System.out.println( TestUtil.getMetaModelSourceAsString( Employee.class ) );
+		System.out.println( TestUtil.getMetaModelSourceAsString( AnotherEmployee.class ) );
+		System.out.println( TestUtil.getMetaModelSourceAsString( Address.class ) );
+		System.out.println( TestUtil.getMetaModelSourceAsString( EmployeeWithIdClass.class ) );
+
+		checkIfIdClassIsGenerated( Employee.class, new String[] {"empName", "empId"} );
+		checkIfIdClassIsGenerated( AnotherEmployee.class, new String[] {"empId", "empName"} );
+
+		final var clazz = getMetamodelClassFor( EmployeeWithIdClass.class );
+		assertTrue( Arrays.stream( clazz.getClasses() ).map( Class::getSimpleName )
+						.noneMatch( "Id"::equals ),
+				"EmployeeWithIdClass_ should not have inner class Id" );
+	}
+
+	private static void checkIfIdClassIsGenerated(Class<?> entityClass, String[] idComponentNames) {
+		final var clazz = getMetamodelClassFor( entityClass );
+		final var maybeIdClass = Arrays.stream( clazz.getClasses() )
+				.filter( c -> c.getSimpleName().equals( "Id" ) ).findAny();
+		assertTrue( maybeIdClass.isPresent(), () -> clazz.getSimpleName() + "_ should have inner class Id" );
+		final Class<?> idClass = maybeIdClass.get();
+		assertTrue( idClass.isRecord(), "Generated ID class should be a record" );
+		assertArrayEquals(
+				idComponentNames,
+				Arrays.stream( idClass.getRecordComponents() ).map( RecordComponent::getName ).toArray( String[]::new )
+		);
+	}
+}

tooling/metamodel-generator/src/test/java/org/hibernate/processor/test/hhh18829/Employee.java

@@ -0,0 +1,17 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.processor.test.hhh18829;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+
+@Entity
+public class Employee extends Address {
+	@Id
+	String empName;
+	@Id
+	Integer empId;
+
+}

tooling/metamodel-generator/src/test/java/org/hibernate/processor/test/hhh18829/EmployeeWithIdClass.java

@@ -0,0 +1,22 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.processor.test.hhh18829;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.IdClass;
+
+@Entity
+@IdClass(EmployeeWithIdClass.EmployeeId.class)
+public class EmployeeWithIdClass extends Address {
+	@Id
+	String empName;
+	@Id
+	Integer empId;
+
+	public record EmployeeId(String empName, Integer empId) {
+	}
+
+}