MONDRIAN: In the XMLA server, don't assume that MetadataElement.toStr…

…ing() is

    equivalent to MetadataElement.getUniqueName(). Fixed the sole violation.

[git-p4: depot-paths = "//open/mondrian/": change = 14308]

src/main/mondrian/xmla/RowsetDefinition.java

@@ -4494,7 +4494,9 @@ protected void populateHierarchy(
             int cardinality = extra.getHierarchyCardinality(hierarchy);
             row.set(HierarchyCardinality.name, cardinality);
 
-            row.set(DefaultMember.name, hierarchy.getDefaultMember());
+            row.set(
+                DefaultMember.name,
+                hierarchy.getDefaultMember().getUniqueName());
             if (hierarchy.hasAll()) {
                 row.set(
                     AllMember.name,