问为什么Java 8没有在`java.util.concurrent.locks.Lock`接口中添加“WithLock‘默认方法”？

EN

public default void withLock(Runnable r) {
  lock();

  try {
     r.run();
  } finally {
     unlock();
  }
}

public class ThreadSafe {
  // Object requiring protection
  private final List<String> l = new ArrayList<>();
  private final Lock lock = new ReentrantLock();

  public void mutate(String s) {
    lock.withLock(() -> l.add(s));
  }

  public void threadSafeMethod {
    lock.withLock(() -> { System.out.println(l.get(l.size())); });
  }
}

public void threadSafeMethod {
  lock.lock();
  try {
    System.out.println(l.get(l.size())); 
  } finally { 
    lock.unlock();
  }
}