为什么这段代码在jdk12中没有引发死锁呢？

包com;
公共类DeadLockDemo {    私有静态字符串A =“ A”;    私有静态字符串B =“ B”;    公共静态void main（String [] args）抛出InterruptedException {        新的DeadLockDemo（）。deadLock（）;    }    私人无效deadLock（）{        线程t1 =新线程（新Runnable（）{@Overridepublic void run（）{                已同步（A）{                    尝试 {                        Thread.currentThread（）。sleep（2000）;                    } catch（InterruptedException e）{                        e.printStackTrace（）;                    }                }                已同步（B）{                    System.out.println（“ 1”）;                }            }        }）;        线程t2 =新线程（新Runnable（）{@Overridepublic void run（）{                已同步（B）{                    已同步（A）{                        System.out.println（“ 2”）;                    }                }            }        }）;        t1.start（）;        t2.start（）;    }}