Use global constant, this and the previous checkin fixes pull request 17 on github

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1691822 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/src/integrationtest/org/apache/poi/stress/XDGFFileHandler.java b/src/integrationtest/org/apache/poi/stress/XDGFFileHandler.java
index 3095cea..4c4fd60 100644
--- a/src/integrationtest/org/apache/poi/stress/XDGFFileHandler.java
+++ b/src/integrationtest/org/apache/poi/stress/XDGFFileHandler.java
@@ -27,6 +27,7 @@
 import org.apache.poi.openxml4j.opc.OPCPackage;
 import org.apache.poi.openxml4j.opc.PackageAccess;
 import org.apache.poi.openxml4j.opc.PackagePart;
+import org.apache.poi.openxml4j.opc.PackageRelationshipTypes;
 import org.apache.poi.util.PackageHelper;
 import org.junit.Test;
 
@@ -59,11 +60,8 @@
 
     // TODO: Get rid of this when full visio ooxml support is added
     private final static class TestXDGFXMLDocument extends POIXMLDocument {
-
-        public static String CORE_DOCUMENT = "http://schemas.microsoft.com/visio/2010/relationships/document";
-
         public TestXDGFXMLDocument(OPCPackage pkg) {
-            super(pkg, CORE_DOCUMENT);
+            super(pkg, PackageRelationshipTypes.VISIO_CORE_DOCUMENT);
         }
 
         public TestXDGFXMLDocument(InputStream is) throws IOException {