"$SAMPLE$" looks like the kind of thing that a template processor would use to reference replaceable variables. However, JSF already has a template processor (EL), so this is a little strange.
In any event. any use of "ui:param" or other code-like constructs in a JSF View Definition (xhtml) should be a very rare occasion. The View Definition is supposed to be a template for the display. Logic should be located in the backing beans. Parameter passing between the two is usually not required because JSF has implicit mechanisms to handle such things.
An IDE is no substitute for an Intelligent Developer.