Currently, it's not possible to do an equivalent of "super.foo()" from the body of a Java class adapter. E.g. in this example where we want a filter writer that capitalizes its output:

var cap = new java.io.FilterWriter(w) {
    write: function(s, off, len) {
        cap.super$write(capitalize(s), off, len)
    }
}

function capitalize(s) { ... } // capitalizes a string

The basic idea is to add methods prefixed with "super$" for every non-abstract overridable method from the adapter's superclass.