The testing for foreach loops was made too restrictive; this code compiled in build 68 and earlier:

    public Void scan(Iterable<? extends Tree> trees, Object o) {
        if (!found && trees == null)
            for (Tree tree : trees)
                if (!found)
                    scan(tree, o);
        return null;
    }

but fails in build 70 with "foreach not applicable to expression type". Since trees is a collection of instances of type Tree or subclasses of type Tree, any element of that collection can safely be assigned to the foreach tree variable.