Xpath Query on Multinode Treepicker no longer working for new Nodes (u…

…mbraco#15159)

* fix for umbraco#14698

* Adjust XPath logic so it uses parentId as $current only when nodeContextId is null or 0

---------

Co-authored-by: Laura Neto <12862535+lauraneto@users.noreply.github.com>

src/Umbraco.Core/Xml/UmbracoXPathPathSyntaxParser.cs

@@ -136,12 +136,12 @@ public static string ParseXPathQuery(
             });
         }
 
-        // These parameters must have a node id context
-        if (nodeContextId.HasValue)
+        if (nodeContextId.HasValue || parentId.HasValue)
         {
+            var currentId = nodeContextId.HasValue && nodeContextId.Value != default ? nodeContextId.Value : parentId.GetValueOrDefault();
             vars.Add("$current", q =>
             {
-                var closestPublishedAncestorId = getClosestPublishedAncestor(getPath(nodeContextId.Value));
+                var closestPublishedAncestorId = getClosestPublishedAncestor(getPath(currentId));
                 return q.Replace("$current", string.Format(rootXpath, closestPublishedAncestorId));
             });
         }