Close the connection, there is a Smack-Ping in the stack

public void closeConnection(){
if(abstractxmppconnection.isConnected()){
PingManager.getInstanceFor(abstractxmppconnection).setPingInterval(-1);
abstractxmppconnection.disconnect();
} else {
//Do-nothing
}//if(abstractxmppconnection.isConnected())
abstractxmppconnection = null;
}

Hello, when I close the connection, I implemented the above method. Why do I still have Smack-Ping when I trace the stack?

“Smack-Ping 0 (0)” #53 daemon prio=5 os_prio=0 tid=0x000000001d138800 nid=0x38fc waiting on condition [0x0000000023ece000]
java.lang.Thread.State: TIMED_WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x0000000082d2b698> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.parkNanos(Unknown Source)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(Unknown Source)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(Unknown Source)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.getTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

Locked ownable synchronizers:
- None