Parse JPA <exclude-unlisted-classes> correctly

Fix PersistenceUnitReader to correctly read <exclude-unlisted-classes>
in both JPA 1.0 and 2.0 persistence.xml files.

Prior to this commit PersistenceUnitReader would set the value of
excludeUnlistedClasses to true when a <exclude-unlisted-classes> element
was present, regardless of its value.

The following rules are now used when parsing:

- If the <exclude-unlisted-classes> element is missing the appropriate
  default value is set (based on the JPA version).

- If an empty <exclude-unlisted-classes/> element is found the
  excludeUnlistedClasses property is set to true.

- Otherwise the value of the <exclude-unlisted-classes> element is used
  to set the excludeUnlistedClasses property.

Issue: SPR-10767

spring-orm/src/main/java/org/springframework/orm/jpa/persistenceunit/PersistenceUnitReader.java

@@ -21,6 +21,7 @@ import java.io.InputStream;
 import java.net.URL;
 import java.util.LinkedList;
 import java.util.List;
+
 import javax.persistence.SharedCacheMode;
 import javax.persistence.ValidationMode;
 import javax.persistence.spi.PersistenceUnitTransactionType;
@@ -34,7 +35,6 @@ import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.xml.sax.ErrorHandler;
 import org.xml.sax.SAXException;
-
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.support.ResourcePatternResolver;
 import org.springframework.jdbc.datasource.lookup.DataSourceLookup;
@@ -83,6 +83,8 @@ class PersistenceUnitReader {
 
 	private static final String META_INF = "META-INF";
 
+	private static final String VERSION_1 = "1.0";
+
 
 	private final Log logger = LogFactory.getLog(getClass());
 
@@ -268,8 +270,14 @@ class PersistenceUnitReader {
 
 		// exclude unlisted classes
 		Element excludeUnlistedClasses = DomUtils.getChildElementByTagName(persistenceUnit, EXCLUDE_UNLISTED_CLASSES);
-		if (excludeUnlistedClasses != null) {
-			unitInfo.setExcludeUnlistedClasses(true);
+		if (excludeUnlistedClasses == null) {
+			// element is not defined, use default appropriate for version
+			unitInfo.setExcludeUnlistedClasses(!VERSION_1.equals(version));
+		}
+		else {
+			String excludeText = DomUtils.getTextValue(excludeUnlistedClasses);
+			unitInfo.setExcludeUnlistedClasses(StringUtils.isEmpty(excludeText) ||
+					Boolean.valueOf(excludeText));
 		}
 
 		// set JPA 2.0 shared cache mode