Remove unused HibernateCallback interface

See gh-33750

spring-orm/src/main/java/org/springframework/orm/hibernate5/HibernateCallback.java

@@ -1,55 +0,0 @@
-/*
- * Copyright 2002-2018 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.orm.hibernate5;
-
-import org.hibernate.HibernateException;
-import org.hibernate.Session;
-
-import org.springframework.lang.Nullable;
-
-/**
- * Callback interface for Hibernate code. To be used with {@link HibernateTemplate}'s
- * execution methods, often as anonymous classes within a method implementation.
- * A typical implementation will call {@code Session.load/find/update} to perform
- * some operations on persistent objects.
- *
- * @author Juergen Hoeller
- * @since 4.2
- * @param <T> the result type
- * @see HibernateTemplate
- * @see HibernateTransactionManager
- */
-@FunctionalInterface
-public interface HibernateCallback<T> {
-
-	/**
-	 * Gets called by {@code HibernateTemplate.execute} with an active
-	 * Hibernate {@code Session}. Does not need to care about activating
-	 * or closing the {@code Session}, or handling transactions.
-	 * <p>Allows for returning a result object created within the callback,
-	 * i.e. a domain object or a collection of domain objects.
-	 * A thrown custom RuntimeException is treated as an application exception:
-	 * It gets propagated to the caller of the template.
-	 * @param session active Hibernate session
-	 * @return a result object, or {@code null} if none
-	 * @throws HibernateException if thrown by the Hibernate API
-	 * @see HibernateTemplate#execute
-	 */
-	@Nullable
-	T doInHibernate(Session session) throws HibernateException;
-
-}

spring-orm/src/main/java/org/springframework/orm/hibernate5/HibernateTransactionManager.java

@@ -771,10 +771,9 @@ public class HibernateTransactionManager extends AbstractPlatformTransactionMana
 	/**
 	 * Disconnect a pre-existing Hibernate Session on transaction completion,
 	 * returning its database connection but preserving its entity state.
-	 * <p>The default implementation calls the equivalent of {@link Session#disconnect()}.
-	 * Subclasses may override this with a no-op or with fine-tuned disconnection logic.
+	 * <p>The default implementation triggers a manual disconnect. Subclasses
+	 * may override this with a no-op or with fine-tuned disconnection logic.
 	 * @param session the Hibernate Session to disconnect
-	 * @see Session#disconnect()
 	 */
 	protected void disconnectOnCompletion(Session session) {
 		if (session instanceof SessionImplementor sessionImpl) {