From 80219f38cbc0848ef052b4e7c4e331304ee80fe2 Mon Sep 17 00:00:00 2001
From: tastybento <tastybento@users.noreply.github.com>
Date: Sat, 7 Sep 2024 11:06:51 -0700
Subject: [PATCH] Add protection around meta data being written that is
 immutable

---
 .../bentobox/database/objects/Players.java    | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/src/main/java/world/bentobox/bentobox/database/objects/Players.java b/src/main/java/world/bentobox/bentobox/database/objects/Players.java
index ca384ed12..883072d7c 100644
--- a/src/main/java/world/bentobox/bentobox/database/objects/Players.java
+++ b/src/main/java/world/bentobox/bentobox/database/objects/Players.java
@@ -253,10 +253,32 @@ public class Players implements DataObject, MetaDataAble {
     public Optional<Map<String, MetaDataValue>> getMetaData() {
         if (metaData == null) {
             metaData = new HashMap<>();
+        } else if (isImmutable(metaData)) {
+            metaData = new HashMap<>(metaData); // Convert immutable map to mutable
         }
         return Optional.of(metaData);
     }
 
+    private boolean isImmutable(Map<String, MetaDataValue> map) {
+        try {
+            String testKey = "testKey";
+            MetaDataValue testValue = new MetaDataValue("test");
+
+            // If the map already contains keys, use one of them
+            if (!map.isEmpty()) {
+                String existingKey = map.keySet().iterator().next();
+                map.put(existingKey, map.get(existingKey)); // Attempt to replace value
+            } else {
+                // Use a unique key-value pair
+                map.put(testKey, testValue);
+                map.remove(testKey);
+            }
+            return false; // No exception means the map is mutable
+        } catch (UnsupportedOperationException e) {
+            return true; // Exception means the map is immutable
+        }
+    }
+
     /**
      * @param metaData the metaData to set
      * @since 1.15.4
@@ -264,6 +286,9 @@ public class Players implements DataObject, MetaDataAble {
      */
     @Override
     public void setMetaData(Map<String, MetaDataValue> metaData) {
+        if (isImmutable(metaData)) {
+            throw new IllegalArgumentException("Provided map is immutable and cannot be set.");
+        }
         this.metaData = metaData;
     }