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

public class NestedSynchronizedBlocks {
  class MyClass {
    public Object field;
  }

  @GuardedBy("lock1") MyClass m1;

  @GuardedBy("lock2") MyClass m2;

  @GuardedBy("lock3") MyClass m3;

  @GuardedBy("lock4") MyClass m4;

  final Object lock1 = new Object(),
      lock2 = new Object(),
      lock3 = new Object(),
      lock4 = new Object();

  void foo() {
    synchronized (lock1) {
      synchronized (lock2) {
        synchronized (lock3) {
          synchronized (lock4) {
          }
        }
      }
    }

    // Test that the locks are known to have been released.

    // :: error:(lock.not.held)
    m1.field = new Object();
    // :: error:(lock.not.held)
    m2.field = new Object();
    // :: error:(lock.not.held)
    m3.field = new Object();
    // :: error:(lock.not.held)
    m4.field = new Object();
  }
}