Router and URLs with extra stuff at the end

[Stokes]

If I have a router with two Restlets attached as follows:
   /foos          ==> FooListFinder
   /foos/{fooId}  ==> FooFinder

... then, as expected, these request route as follows:
   /foos                      --routes to-->  FooListFinder
   /foos?somearg=true         --routes to-->  FooListFinder
   /foos/123                  --routes to-->  FooFinder
   /foos/123?someotherarg=456 --routes to-->  FooFinder

All of that is good.

But as a side-effect, I get these that I _don't_ want:
   /foos/123/garbage          --routes to-->  FooFinder
   /foos/123/more/garbage     --routes to-->  FooFinder

Any suggestions for how to prevent these last two?  I need to handle this at the
framework/router level, so that the Finder implementations aren't concerned.

In my case my API is very particular about syntax, so I want the last two
requests above to result in an error page (400).

Thanks,
Stokes.