Investigate NullPointerException in vehicleposition processor

[LofhJann]

https://github.com/HSLdevcom/transitdata-vehicleposition-processor is logging loads of NullPointerExceptions coming from fi.hsl.transitdata.vehicleposition.application.VehiclePositionHandler

Investigate the cause and fix problem and/or improve error handling

[LofhJann]

Could be related to fi.hsl.transitdata.omm.OmmCancellationHandler. From first glance it seems these logs are usually seen together with Produced entire departure cancellation for trip: xxxx/<TIMESTAMP> so it could be that trips that have been cancelled lack some information that vehicleposition-processor is trying to use.

Following this line of theory, if proven wrong this is mostly a non-problem but error handling should be improved to avoid logs filling with unnecessary NPEs either way.

[LofhJann]

Optional<PassengerCount.Payload> maybePayload = passengerCountParser.parsePayload(apcJson);

This line is likely culprit. parsePayload() isn't returning Optional.Empty in case of exceptions as it likely should. Requires more investigation but likely this.

Root cause is deeper
Caused by: com.dslplatform.json.ParsingException: Leading zero is not allowed. Error parsing number at position: 257, following: oc": "GPS", "stop": , before: 00000, "route": "457
Could be wrong data type somewhere? (Integers can't have leading zeroes so if such is case it should be String instead)