AssertJ Swing - kill all fixtures

Is there a way how to kill all AssertJ created fixtures, or how to prevent hanging, when creating a new one? When trying to migrate a lot of legacy GUI tests to AssertJ Swing, I have to often face the following deadlock:

"main" #1 prio=5 os_prio=0 tid=0x0000000002080000 nid=0x9c waiting on condition [0x00000000024cd000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x0000000547049720> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
    at org.assertj.swing.lock.ScreenLock.acquire(ScreenLock.java:57)
    at org.assertj.swing.core.BasicRobot.acquireScreenLock(BasicRobot.java:164)
    at org.assertj.swing.core.BasicRobot.robotWithCurrentAwtHierarchy(BasicRobot.java:153)
    at org.assertj.swing.fixture.AbstractWindowFixture.<init>(AbstractWindowFixture.java:119)
    at org.assertj.swing.fixture.FrameFixture.<init>(FrameFixture.java:43)

This is of course caused by wrong usage of fixtures, when a new one is being created while another one is still active. However, this deadlock complicates the migration.

Solution

After exploring the framework more, I have realized that

I do not need to use locking
It is possible to release the lock, if I create the robot myself

Now I am using this code to create the fixture:

assertJRobot = BasicRobot.robotWithCurrentAwtHierarchy();
frameFixture = new FrameFixture(assertJRobot, appFrame());

And this code when I need to create another fixture, while the other test did not release the lock but otherwise closed windows, and cleaned up everything else:

assertJRobot.cleanUpWithoutDisposingWindows();