OverspeedEventHandler

we have this code in OverspeedEventHandler class:

double speedLimit = AttributeUtil.lookup(cacheManager, Keys.EVENT_OVERSPEED_LIMIT, deviceId);

but we save speed limit in attributes of device class. why we do not get speedlimit from device class?

It's not possible to answer your question with the information provided. If you don't get it, there must be a reason for it.

I explain more
We can add speed limit attribute while add device and this attribute save in device table .
I expect the traacar use this attribute in the device table for finding events with overspeedexceeded .but
The traccar use the below variable in code :double speedLimit = AttributeUtil.lookup(cacheManager, Keys.EVENT_OVERSPEED_LIMIT, deviceId);

public OverspeedEventHandler(Config config, CacheManager cacheManager, Storage storage) {
        this.cacheManager = cacheManager;
        this.storage = storage;
        minimalDuration = config.getLong(Keys.EVENT_OVERSPEED_MINIMAL_DURATION) * 1000;
        preferLowest = config.getBoolean(Keys.EVENT_OVERSPEED_PREFER_LOWEST);
        multiplier = config.getDouble(Keys.EVENT_OVERSPEED_THRESHOLD_MULTIPLIER);
    }

    @Override
    public void analyzePosition(Position position, Callback callback) {

        long deviceId = position.getDeviceId();
        Device device = cacheManager.getObject(Device.class, position.getDeviceId());
        if (device == null) {
            return;
        }
        if (!PositionUtil.isLatest(cacheManager, position) || !position.getValid()) {
            return;
        }

        double speedLimit = AttributeUtil.lookup(cacheManager, Keys.EVENT_OVERSPEED_LIMIT, deviceId);

        double positionSpeedLimit = position.getDouble(Position.KEY_SPEED_LIMIT);
        if (positionSpeedLimit > 0) {
            speedLimit = positionSpeedLimit;
        }

        double geofenceSpeedLimit = 0;
        long overspeedGeofenceId = 0;

        if (position.getGeofenceIds() != null) {
            for (long geofenceId : position.getGeofenceIds()) {
                Geofence geofence = cacheManager.getObject(Geofence.class, geofenceId);
                if (geofence != null) {
                    double currentSpeedLimit = geofence.getDouble(Keys.EVENT_OVERSPEED_LIMIT.getKey());
                    if (currentSpeedLimit > 0 && geofenceSpeedLimit == 0
                            || preferLowest && currentSpeedLimit < geofenceSpeedLimit
                            || !preferLowest && currentSpeedLimit > geofenceSpeedLimit) {
                        geofenceSpeedLimit = currentSpeedLimit;
                        overspeedGeofenceId = geofenceId;
                    }
                }
            }
        }
        if (geofenceSpeedLimit > 0) {
            speedLimit = geofenceSpeedLimit;
        }

        if (speedLimit == 0) {
            return;
        }

        OverspeedState state = OverspeedState.fromDevice(device);
        OverspeedProcessor.updateState(state, position, speedLimit, multiplier, minimalDuration, overspeedGeofenceId);
        if (state.isChanged()) {
            state.toDevice(device);
            try {
                storage.updateObject(device, new Request(
                        new Columns.Include("overspeedState", "overspeedTime", "overspeedGeofenceId"),
                        new Condition.Equals("id", device.getId())));
            } catch (StorageException e) {
                LOGGER.warn("Update device overspeed error", e);
            }
        }
        if (state.getEvent() != null) {
            callback.eventDetected(state.getEvent());
        }
    }

}

This looks like outdated code. Also why post the code here instead of just link?

https://github.com/traccar/traccar/blob/master/src/main/java/org/traccar/helper/model/AttributeUtil.java

This code in master branch