InvocationHandler that translates between exception types... probably not useful

gistfile1.java

    static class ExceptionTranslatingForwardingInvocationHandler implements InvocationHandler {

        private final ImmutableMap<Class<? extends Throwable>, Class<? extends Throwable>> exceptionMap;
        private final Object delegate;

        ExceptionTranslatingForwardingInvocationHandler(
            Map<Class<? extends Throwable>, Class<? extends Throwable>> exceptionMap,
            Object delegate) {

            this.exceptionMap = ImmutableMap.copyOf(exceptionMap);
            this.delegate = delegate;
        }

        @Override
        public Object invoke(Object o, Method method, Object[] args) throws Throwable {
            try {
                return method.invoke(delegate, args);
            } catch (InvocationTargetException e) {
                Throwable cause = e.getCause();
                for (Class<? extends Throwable> clazz : exceptionMap.keySet()) {
                    if (clazz.getClass().isInstance(cause)) {
                        throw exceptionMap.get(clazz).newInstance();
                    }
                }
                throw cause;
            } catch (IllegalAccessException e) {
                // won't happen.
                throw new IllegalStateException("Invocation handler caught illegal access exn.");
            }
        }
    }