HHH-18466 Failing test to demonstrate

https://hibernate.atlassian.net/browse/HHH-18466

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/identifier/MutableNaturalIdsTest.java

@@ -0,0 +1,151 @@
+/*
+ * 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.mapping.identifier;
+
+import static org.hibernate.testing.transaction.TransactionUtil.doInJPA;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+
+import org.hibernate.Session;
+import org.hibernate.annotations.NaturalId;
+import org.hibernate.internal.SessionImpl;
+import org.hibernate.orm.test.jpa.BaseEntityManagerFunctionalTestCase;
+import org.junit.Test;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+
+/**
+ * @author Gary Gregory
+ */
+public class MutableNaturalIdsTest extends BaseEntityManagerFunctionalTestCase {
+
+	private static final String FIELD_1 = "email1";
+	private static final String FIELD_2 = "email2";
+	private static final String FIELD_3 = "email3";
+
+	private static final String OLD_VALUE_1 = "john1@acme.com";
+	private static final String OLD_VALUE_2 = "john2@acme.com";
+	private static final String OLD_VALUE_3 = "john3@acme.com";
+
+	private static final String NEW_VALUE_1 = "john.doe1@acme.com";
+	private static final String NEW_VALUE_2 = "john.doe2@acme.com";
+
+	@Override
+	protected Class<?>[] getAnnotatedClasses() {
+		return new Class<?>[] {
+			Author.class
+		};
+	}
+
+	@Test
+	public void test() {
+		doInJPA(this::entityManagerFactory, entityManager -> {
+			Author author = new Author();
+			author.setId(1L);
+			author.setName("John Doe");
+			author.setEmail1(OLD_VALUE_1);
+			author.setEmail2(OLD_VALUE_2);
+			author.setEmail3(OLD_VALUE_3);
+
+			entityManager.persist(author);
+		});
+		doInJPA(this::entityManagerFactory, entityManager -> {
+			Author author = entityManager
+				.unwrap(Session.class)
+				.byNaturalId(Author.class)
+				.using(FIELD_1, OLD_VALUE_1)
+				.using(FIELD_2, OLD_VALUE_2)
+				.using(FIELD_3, OLD_VALUE_3)
+				.load();
+
+			author.setEmail1(NEW_VALUE_1);
+			author.setEmail2(NEW_VALUE_2);
+
+			assertNull(
+				entityManager
+					.unwrap(Session.class)
+					.byNaturalId(Author.class)
+					.setSynchronizationEnabled(false)
+					.using(FIELD_1, NEW_VALUE_1)
+					.using(FIELD_2, NEW_VALUE_2)
+					.using(FIELD_3, OLD_VALUE_3)
+					.load()
+			);
+
+			assertSame(author,
+				entityManager
+					.unwrap(Session.class)
+					.byNaturalId(Author.class)
+					.setSynchronizationEnabled(true)
+					.using(FIELD_1, NEW_VALUE_1)
+					.using(FIELD_2, NEW_VALUE_2)
+					.using(FIELD_3, OLD_VALUE_3)
+					.load()
+			);
+		});
+	}
+
+	@Entity(name = "Author")
+	public static class Author {
+
+		@Id
+		private Long id;
+
+		private String name;
+
+		@NaturalId(mutable = true)
+		private String email1;
+
+		@NaturalId(mutable = true)
+		private String email2;
+
+		@NaturalId
+		private String email3;
+
+		public Long getId() {
+			return id;
+		}
+
+		public void setId(Long id) {
+			this.id = id;
+		}
+
+		public String getName() {
+			return name;
+		}
+
+		public void setName(String name) {
+			this.name = name;
+		}
+
+		public String getEmail1() {
+			return email1;
+		}
+
+		public String getEmail2() {
+			return email2;
+		}
+
+		public String getEmail3() {
+			return email3;
+		}
+
+		public void setEmail1(String email) {
+			this.email1 = email;
+		}
+
+		public void setEmail2(String email2) {
+			this.email2 = email2;
+		}
+
+		public void setEmail3(String email3) {
+			this.email3 = email3;
+		}
+
+	}
+}