HHH-15359 Add test for issue

hibernate-core/src/test/java/org/hibernate/orm/test/annotations/embeddables/EmbeddableWithManyToManyTest.java

@@ -0,0 +1,142 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+package org.hibernate.orm.test.annotations.embeddables;
+
+import java.util.Arrays;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import org.hibernate.testing.TestForIssue;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.CascadeType;
+import jakarta.persistence.Embeddable;
+import jakarta.persistence.Embedded;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.ManyToMany;
+import jakarta.persistence.Table;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@DomainModel(
+		annotatedClasses = {
+				EmbeddableWithManyToManyTest.Product.class,
+				EmbeddableWithManyToManyTest.User.class
+		}
+)
+@SessionFactory
+@TestForIssue(jiraKey = "HHH-15453")
+public class EmbeddableWithManyToManyTest {
+
+	@Test
+	public void testMerge(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					User user = new User( 1L, "Fab" );
+					session.persist( user );
+
+					Product product = new Product( 2L, "Sugar", new Users( user ) );
+					Product mergedProduct = session.merge( product );
+					assertThat( mergedProduct.getUsers().getUsers() ).isNotNull();
+				}
+		);
+
+		scope.inTransaction(
+				session -> {
+					Product product = session.get( Product.class, 2L );
+					assertThat( product ).isNotNull();
+					assertThat( product.getUsers().getUsers() ).isNotNull();
+				}
+		);
+	}
+
+	@Entity(name = "Product")
+	public static class Product {
+		@Id
+		private Long id;
+
+		private String name;
+
+		@Embedded
+		private Users users;
+
+		public Product() {
+		}
+
+		public Product(Long id, String name, Users users) {
+			this.id = id;
+			this.name = name;
+			this.users = users;
+		}
+
+		public Long getId() {
+			return id;
+		}
+
+		public String getName() {
+			return name;
+		}
+
+		public Users getUsers() {
+			return users;
+		}
+	}
+
+	@Embeddable
+	public static class Users {
+
+		private Integer initial;
+
+		@ManyToMany(cascade = { CascadeType.PERSIST, CascadeType.MERGE })
+		private Set<User> users;
+
+		public Users() {
+		}
+
+		public Users(User... users) {
+			this.users = Arrays.stream( users ).collect( Collectors.toSet() );
+			initial = users.length;
+		}
+
+		public Set<User> getUsers() {
+			return users;
+		}
+
+		public void setUsers(Set<User> users) {
+			this.users = users;
+		}
+	}
+
+	@Entity(name = "User")
+	@Table(name = "USER_TABLE")
+	public static class User {
+		@Id
+		private Long id;
+
+		private String name;
+
+		public User() {
+		}
+
+		public User(Long id, String name) {
+			this.id = id;
+			this.name = name;
+		}
+
+		public Long getId() {
+			return id;
+		}
+
+		public String getName() {
+			return name;
+		}
+	}
+}