Update javadoc for .fetch + tests

hibernate-reactive-core/src/main/java/org/hibernate/reactive/mutiny/Mutiny.java

@@ -848,16 +848,23 @@ default Uni<Void> lock(Object entity, LockModeType lockModeType) {
 
 		/**
 		 * Asynchronously fetch an association that's configured for lazy loading.
-		 *
+		 * <p>
 		 * <pre>
 		 * {@code session.fetch(author.getBook()).thenAccept(book -> print(book.getTitle()));}
 		 * </pre>
-		 *
-		 * @param association a lazy-loaded association
+		 * </p>
+		 * <p>
+		 * It can also initialize proxys. For example:
+		 * <pre>
+		 * {@code session.fetch(session.getReference(Author.class, authorId))}
+		 * </pre>
+		 * </p>
+		 * @param association a lazy-loaded association, or a proxy
 		 *
 		 * @return the fetched association, via a {@code Uni}
 		 *
 		 * @see Mutiny#fetch(Object)
+		 * @see #getReference(Class, Object)
 		 * @see org.hibernate.Hibernate#initialize(Object)
 		 */
 		<T> Uni<T> fetch(T association);

hibernate-reactive-core/src/main/java/org/hibernate/reactive/stage/Stage.java

@@ -877,16 +877,24 @@ default CompletionStage<Void> lock(Object entity, LockModeType lockModeType) {
 
 		/**
 		 * Asynchronously fetch an association that's configured for lazy loading.
-		 *
+		 * <p>
 		 * <pre>
 		 * {@code session.fetch(author.getBook()).thenAccept(book -> print(book.getTitle()))}
 		 * </pre>
+		 * </p>
+		 * <p>
+		 * It can also initialize proxys. For example:
+		 * <pre>
+		 * {@code session.fetch(session.getReference(Author.class, authorId))}
+		 * </pre>
+		 * </p>
 		 *
-		 * @param association a lazy-loaded association
+		 * @param association a lazy-loaded association, or a proxy
 		 *
 		 * @return the fetched association, via a {@code CompletionStage}
 		 *
 		 * @see Stage#fetch(Object)
+		 * @see #getReference(Class, Object)
 		 * @see org.hibernate.Hibernate#initialize(Object)
 		 */
 		<T> CompletionStage<T> fetch(T association);

hibernate-reactive-core/src/test/java/org/hibernate/reactive/ReferenceTest.java

@@ -30,6 +30,7 @@
 import jakarta.persistence.Version;
 
 import static java.util.concurrent.TimeUnit.MINUTES;
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.hibernate.reactive.util.impl.CompletionStages.loop;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
@@ -231,6 +232,25 @@ public void testRefreshDetachedProxy(VertxTestContext context) {
 		);
 	}
 
+	@Test
+	public void testFetchOfReference(VertxTestContext context) {
+		final Book goodOmens = new Book( "Good Omens: The Nice and Accurate Prophecies of Agnes Nutter, Witch" );
+		final Author neil = new Author( "Neil Gaiman", goodOmens );
+		final Author terry = new Author( "Terry Pratchett", goodOmens );
+		goodOmens.getAuthors().add( neil );
+		goodOmens.getAuthors().add( terry );
+
+		test( context, getMutinySessionFactory()
+				.withTransaction( s -> s.persistAll( goodOmens, terry, neil ) )
+				.call( () -> getMutinySessionFactory().withSession( s -> s
+						// Not the most common case, but should be possible
+						.fetch( s.getReference( Book.class, goodOmens.getId() ) )
+						.chain( reference -> s.fetch( reference.getAuthors() ) )
+						.invoke( authors -> assertThat( authors ).containsExactlyInAnyOrder( terry, neil ) )
+				) )
+		);
+	}
+
 	@Entity(name = "Tome")
 	@Table(name = "TBook")
 	public static class Book {

integration-tests/bytecode-enhancements-it/src/test/java/org/hibernate/reactive/it/ReferenceBETest.java

@@ -22,6 +22,7 @@
 import io.vertx.junit5.VertxTestContext;
 
 import static java.util.concurrent.TimeUnit.MINUTES;
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.hibernate.reactive.util.impl.CompletionStages.completedFuture;
 import static org.hibernate.reactive.util.impl.CompletionStages.loop;
 import static org.junit.jupiter.api.Assertions.assertEquals;
@@ -212,4 +213,23 @@ public void testRefreshDetachedProxy(VertxTestContext context) {
 					  ) )
 		);
 	}
+
+	@Test
+	public void testFetchOfReference(VertxTestContext context) {
+		final Book goodOmens = new Book( "Good Omens: The Nice and Accurate Prophecies of Agnes Nutter, Witch" );
+		final Author neil = new Author( "Neil Gaiman", goodOmens );
+		final Author terry = new Author( "Terry Pratchett", goodOmens );
+		goodOmens.getAuthors().add( neil );
+		goodOmens.getAuthors().add( terry );
+
+		test( context, getMutinySessionFactory()
+				.withTransaction( s -> s.persistAll( goodOmens, terry, neil ) )
+				.call( () -> getMutinySessionFactory().withSession( s -> s
+						// Not the most common case, but should be possible
+						.fetch( s.getReference( Book.class, goodOmens.getId() ) )
+						.chain( reference -> s.fetch( reference.getAuthors() ) )
+						.invoke( authors -> assertThat( authors ).containsExactlyInAnyOrder( terry, neil ) )
+				) )
+		);
+	}
 }