set vaadin.resources.path in Websphere

Hi,
I have to set the vaadin.resources.path variable in Websphere 8.5.
I tried with the ‘WP PortletContainerService’ in Resources>Resource Environment>Resource Environment Providers and I set a resource with name ‘std.portalcontext.vaadin.resources.path’ but I can’t see it in UI.
Someone can help me?

​Thank You