private void checkAisPacket(AisPacket p) {
AisMessage msg = p.tryGetAisMessage();
if (msg == null) {
throw new IllegalArgumentException("Cannot extract AisMessage from AisPacket: " + p.toString());
}
<BUG>if (msg.getUserId() != mmsi) {

throw new IllegalArgumentException("This track only accepts updates for MMSI " + mmsi + ", not " + msg.getUserId() + ".");
</BUG>
}

private void checkAisPacket(AisPacket p) {
AisMessage msg = p.tryGetAisMessage();
if (msg == null) {
throw new IllegalArgumentException("Cannot extract AisMessage from AisPacket: " + p.toString());
