Since some of the ctkXnatObject support retrieving a last modification time (e.g. project)

this function should be virtual so that is can be overwritten by the according subclasses

Libs/XNAT/Core/ctkXnatObject.h

@@ -78,7 +78,7 @@ public:
   void setProperty(const QString& name, const QVariant& value);
 
   /// Gets the last modification time from the server
-  QDateTime lastModifiedTimeOnServer();
+  virtual QDateTime lastModifiedTimeOnServer();
 
   /// Sets the last modfication time on the server
   void setLastModifiedTime(const QDateTime& lastModifiedTime);