In the following lambda:

[1:33:03 PM] Brian Goetz: static Runnable composeWithExceptions(Runnable a, Runnable b) {
        return () -> {
            try {
                a.run();
            }
            catch (Throwable e1) {
                try {
                    b.run();
                }
                catch (Throwable e2) {
                    e1.addSuppressed(e2);
                }
                finally {
                    throw e1;
                }
            }
            b.run();
        };
    }

The compiler complains that throwing a Throwable is not allowed. If the lambda is refactored to an inner class instance, enhanced rethrow allows e1 to be rethrown.