Update.java

import org.checkerframework.checker.lock.qual.GuardedBy;

class Update {

    void test() {
        Object o1 = new Object();
        @GuardedBy({}) Object o2 = o1;
        synchronized (o1) {
        }
        // o1 used to loss it refinement because of a bug.
        @GuardedBy({}) Object o3 = o1;
    }
}