Have an inner class declared and invoke format action. 

==> Actual state:

class Test {
    void testMehtod() {
        List list = [];
        list.add(new Runnable() {
                void run() {
                    return true;
                }
            });
    }
}

==> Expected state:

class Test {
    void testMehtod() {
        List list = [];
        list.add(new Runnable() {
            void run() {
                return true;
            }
        });
    }
}