Kairi Kangro has written "On Java Collection Waste," an article in which he examines the wasted heap associated with the standard Java collections library. Short form: they work pretty well.
However, there're a couple of problems with the post. Mr. Kangro abandoned the (implied) hypothesis that the collections were wasteful, partly because Java's garbage collector ran multiple times, cleaning up the heap before actual effects could be accurately measured; that doesn't sound like a validation of the collections framework, but more proof that the JVM works well such that the collections don't need to be spectacularly efficient.
That's not the same thing as "the collections aren't wasteful," or even "the collections aren't wasteful enough to worry about.."
It's an interesting thought. How would you accurately measure the waste associated with collections?
One consideration is that the collections do different things; you'd want to have a measurement for Sets, Lists, and Maps; then you'd want to have a way to populate the collections both sparsely and abundantly, perhaps changing from one state to the other. You'd also want to do so multiple times, to let HotSpot do its work - and with multiple garbage collectors (and potentially multiple JVMs.)
There's a lot of possibility here, even though it might imply some work; who knows, the JDK may already have such measurements.
With all that said, it sure would be useful to have an assertion and related validation (or counterproof) publicly available.