Don't allow players to be added to SubscriptionValueMaps

bukkit/src/main/java/me/lucko/luckperms/bukkit/model/server/LPSubscriptionMap.java

@@ -161,6 +161,9 @@ public final class LPSubscriptionMap extends HashMap<String, Map<Permissible, Bo
         private LPSubscriptionValueMap(String permission, Map<Permissible, Boolean> backing) {
             this.permission = permission;
             this.backing = backing;
+
+            // remove all players from the map
+            this.backing.keySet().removeIf(p -> p instanceof Player);
         }
 
         public LPSubscriptionValueMap(String permission) {
@@ -197,6 +200,16 @@ public final class LPSubscriptionMap extends HashMap<String, Map<Permissible, Bo
             return null;
         }
 
+        @Override
+        public Boolean put(Permissible key, Boolean value) {
+            // don't allow players to be put into this map
+            if (key instanceof Player) {
+                return true;
+            }
+
+            return this.backing.put(key, value);
+        }
+
         @Override
         public boolean containsKey(Object key) {
             // delegate through the get method
@@ -241,11 +254,6 @@ public final class LPSubscriptionMap extends HashMap<String, Map<Permissible, Bo
 
         // just delegate to the backing map
 
-        @Override
-        public Boolean put(Permissible key, Boolean value) {
-            return this.backing.put(key, value);
-        }
-
         @Override
         public Boolean remove(Object key) {
             return this.backing.remove(key);