public override void Execute(IDiagramNode diagramNode)
        {
            var modelEntity = diagramNode?.ModelEntity;

            if (modelEntity == null)
            {
                throw new Exception("Entity missing in DiagramNode.");
            }

            if (ModelServices.HasSource(modelEntity))
            {
                ModelServices.ShowSource(modelEntity);
            }
            else
            {
                UiServices.ShowPopupMessage(NoSourceMessage, NoSourceMessageDuration);
            }
        }