HHH-15235 Add test for issue

Author: dreab8

hibernate-core/src/test/java/org/hibernate/orm/test/annotations/onetoone/EmbeddedIdTest.java

@@ -0,0 +1,83 @@
+/*
+ * 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.onetoone;
+
+import java.io.Serializable;
+
+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.EmbeddedId;
+import jakarta.persistence.Entity;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.OneToOne;
+
+@TestForIssue(jiraKey = "HHH-15235")
+@DomainModel(
+		annotatedClasses = {
+				EmbeddedIdTest.Bar.class,
+				EmbeddedIdTest.Foo.class
+		}
+)
+@SessionFactory
+public class EmbeddedIdTest {
+
+	@Test
+	public void testMerge(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					FooId fooId = new FooId();
+					fooId.id = "foo";
+					Foo foo = new Foo();
+					foo.id = fooId;
+					Bar bar = new Bar();
+					BarId barId = new BarId();
+					barId.id = 1l;
+					bar.id = barId;
+					foo.bar = bar;
+					bar.foo = foo;
+					session.merge( foo );
+					session.flush();
+				}
+		);
+	}
+
+	@Embeddable
+	public static class BarId implements Serializable {
+		private Long id;
+	}
+
+	@Embeddable
+	public static class FooId implements Serializable {
+		private String id;
+	}
+
+	@Entity
+	public static class Bar {
+		@EmbeddedId
+		private BarId id;
+
+		@OneToOne(mappedBy = "bar")
+		private Foo foo;
+	}
+
+	@Entity
+	public static class Foo {
+		@EmbeddedId
+		private FooId id;
+
+		@OneToOne(cascade = CascadeType.ALL)
+		@JoinColumn(name = "bar_id")
+		private Bar bar;
+	}
+}