Change AbilityCache to use ConcurrentHashMap

src/main/java/com/blakebr0/mysticalagriculture/api/lib/AbilityCache.java

@@ -6,11 +6,12 @@
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.stream.Collectors;
 
 public class AbilityCache {
     private static final HashMap<String, Runnable> EMPTY_MAP = new HashMap<>();
-    private final Map<String, Map<String, Runnable>> cache = new HashMap<>();
+    private final Map<String, Map<String, Runnable>> cache = new ConcurrentHashMap<>();
 
     /**
      * Add a user to the cache for the specified augment, meaning they have it equipped currently
@@ -30,7 +31,7 @@ public void add(Augment augment, Player player, Runnable onRemove) {
      */
     public void add(String augment, Player player, Runnable onRemove) {
         var key = getPlayerKey(player);
-        this.cache.computeIfAbsent(augment, s -> new HashMap<>()).put(key, onRemove);
+        this.cache.computeIfAbsent(augment, s -> new ConcurrentHashMap<>()).put(key, onRemove);
     }
 
     /**