generic inference for Collections.checkedMap

[ribrdb]

The signature for checkedMap is:
java.util.Map<K, V> checkedMap(java.util.Map<K, V>, java.lang.Class<K>, java.lang.Class<V>)

if you do Collections.checkedMap({}, Foo.class, Bar.class), the constraints are that K = Object and K = Foo, which is impossible and inference fails. Really what we should be doing here is treating {} as a raw type.