Added GameStateInitEvent.java class (#30)

src/main/java/dev/kavu/gameapi/event/GameStateInitEvent.java

@@ -0,0 +1,30 @@
+package dev.kavu.gameapi.event;
+
+import dev.kavu.gameapi.game.GameState;
+import dev.kavu.gameapi.game.GameType;
+import org.bukkit.event.HandlerList;
+
+public class GameStateInitEvent extends GameStateEvent{
+
+    private static final HandlerList handlers = new HandlerList();
+
+    private final GameState previousState;
+
+    public GameStateInitEvent(GameType gameType, GameState gameState, GameState previousState, boolean scheduled) {
+        super(gameType, gameState, scheduled);
+        this.previousState = previousState;
+    }
+
+    public GameState getPreviousState() {
+        return previousState;
+    }
+
+    @Override
+    public HandlerList getHandlers() {
+        return handlers;
+    }
+
+    public static HandlerList getHandlerList(){
+        return handlers;
+    }
+}