How to solve ClassNotFoundException problem when creating trigger in Apache IoTDB 1.3?

I'm now in Apache IoTDB version 1.3.0 and want to create a simple trigger but encountering class loading issues. My trigger code: `package com.example.trigger;

import org.apache.iotdb.trigger.api.Trigger; import org.apache.iotdb.trigger.api.enums.FailureStrategy; import org.apache.iotdb.tsfile.write.record.Tablet;

public class SimpleAlertTrigger implements Trigger { @Override public void onCreate() { System.out.println("Trigger created"); }

@Override
public void onDrop() {
    System.out.println("Trigger dropped");
}

@Override
public void onStart() {
    System.out.println("Trigger started");
}

@Override
public void onStop() {
    System.out.println("Trigger stopped");
}

@Override
public Integer fire(Tablet tablet) {
    System.out.println("Trigger fired with " + tablet.rowSize + " rows");
    return Trigger.super.fire(tablet);
}

@Override
public FailureStrategy getFailureStrategy() {
    return FailureStrategy.OPTIMISTIC;
}

I've placed the compiled JAR in IoTDB's trigger_root directory and executed:

CREATE TRIGGER `temp_alert`
AFTER INSERT
ON root.aw.rs.d1.temperature
AS 'com.example.trigger.SimpleAlertTrigger'
USING FILE '/iotdb/trigger_root/simple-trigger-1.0.jar'

But getting this error: Msg: 503: Failed to create trigger, because com/example/trigger/SimpleAlertTrigger java.lang.ClassNotFoundException: com.example.trigger.SimpleAlertTrigger.

I've confirmed that JAR file exists at specified path, and JAR contains correct package structure and class files. All the file permissions are also correct. What else could cause this? Are there special requirements for IoTDB trigger class loading?