MockRace:

Now uses RaceState as its base class, rather than Race. This aligns it with VisualiserRace. RaceState contains the shared race state between the client and server, and stores most of its data in RaceDataSource etc..., instead of maintaining its own copy.
Moved collider registry member to MockRace.

XMLUtilities:
Added documentation to two important functions, and updated them to use generics instead of Objects.
#story[1188]

racevisionGame/src/main/java/mock/app/Event.java

@@ -25,6 +25,8 @@ import java.nio.charset.StandardCharsets;
 import java.time.Duration;
 import java.time.ZonedDateTime;
 import java.time.format.DateTimeFormatter;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.concurrent.TimeUnit;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -118,7 +120,8 @@ public class Event {
 
         }
 
-        this.sourceIdAllocator = new SourceIdAllocator(raceDataSource.getParticipants());
+        List<Integer> potentialParticipants = new ArrayList<>(boatDataSource.getBoats().keySet());
+        this.sourceIdAllocator = new SourceIdAllocator(potentialParticipants);
         this.compositeCommand = new CompositeCommand();
         this.latestMessages = new LatestMessages();