Updated 'ShieldState' enumeration.

Updated the 'ShieldState' enumeration by removing unused methods from it.

Projekte/mdga/model/src/main/java/pp/mdga/game/ShieldState.java

@@ -1,11 +1,8 @@
 package pp.mdga.game;
 
-import com.jme3.network.serializing.Serializable;
-
 /**
  * Represents the state of a piece's shield.
  */
-@Serializable
 public enum ShieldState {
     /**
      * The shield is not active.
@@ -19,19 +16,4 @@ public enum ShieldState {
      * The shield is suppressed, when the piece is on a start node.
      */
     SUPPRESSED;
-
-    ShieldState(){
-
-    }
-
-    public static ShieldState getShieldStateByIndex(int index){
-        if (index < 0 || index >= values().length) {
-            throw new IllegalArgumentException("");
-        }
-        return values()[index];
-    }
-
-    public ShieldState next() {
-        return values()[(ordinal() + 1) % values().length];
-    }
 }