OPENJPA-326.  Porting the change for the 1.0.0 branch.

git-svn-id: https://svn.apache.org/repos/asf/openjpa/branches/1.0.0@568756 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/openjpa-persistence-jdbc/src/main/java/org/apache/openjpa/persistence/jdbc/XMLPersistenceMappingParser.java b/openjpa-persistence-jdbc/src/main/java/org/apache/openjpa/persistence/jdbc/XMLPersistenceMappingParser.java
index 6b8c132..daed50c 100644
--- a/openjpa-persistence-jdbc/src/main/java/org/apache/openjpa/persistence/jdbc/XMLPersistenceMappingParser.java
+++ b/openjpa-persistence-jdbc/src/main/java/org/apache/openjpa/persistence/jdbc/XMLPersistenceMappingParser.java
@@ -932,6 +932,9 @@
         if (val != null) {
             _discType = Enum.valueOf(DiscriminatorType.class, val);
         }
+        else {
+            _discType = DiscriminatorType.STRING;
+        }
             
 	}
 }