DATAJPA-138 - Make MergingPesistenceUnitManager work again.

Override isPersistenceUnitOverrideAllowed() newly introduced in Spring 3.1.1 to indicate we can deal with persistence units of the same name. For Spring 3.0.x versions the implementation was not broken.

src/test/java/org/springframework/data/jpa/support/MergingPersistenceUnitManagerUnitTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011 the original author or authors.
+ * Copyright 2011-2012 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.
@@ -15,6 +15,8 @@
  */
 package org.springframework.data.jpa.support;
 
+import static org.hamcrest.Matchers.*;
+import static org.junit.Assert.*;
 import static org.mockito.Mockito.*;
 
 import java.net.MalformedURLException;
@@ -27,6 +29,8 @@ import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.Mock;
 import org.mockito.runners.MockitoJUnitRunner;
+import org.springframework.data.jpa.domain.sample.Role;
+import org.springframework.data.jpa.domain.sample.User;
 import org.springframework.orm.jpa.persistenceunit.MutablePersistenceUnitInfo;
 
 /**
@@ -53,4 +57,17 @@ public class MergingPersistenceUnitManagerUnitTests {
 		manager.postProcessPersistenceUnitInfo(newInfo, oldInfo);
 		verify(newInfo).addJarFileUrl(jarFileUrl);
 	}
+
+	@Test
+	public void mergesManagedClassesCorrectly() {
+
+		MergingPersistenceUnitManager manager = new MergingPersistenceUnitManager();
+		manager.setPersistenceXmlLocations(new String[] { "classpath:org/springframework/data/jpa/support/persistence.xml",
+				"classpath:org/springframework/data/jpa/support/persistence2.xml" });
+		manager.preparePersistenceUnitInfos();
+
+		PersistenceUnitInfo info = manager.obtainPersistenceUnitInfo("pu");
+		assertThat(info.getManagedClassNames().size(), is(2));
+		assertThat(info.getManagedClassNames(), hasItems(User.class.getName(), Role.class.getName()));
+	}
 }