Solved Can't find a codec for class org.bukkit.craftbukkit.v1_16_R3.inventory.CraftMetaItem

I am getting this error when I try to serialize an item stack

Code:

Can't find a codec for class org.bukkit.craftbukkit.v1_16_R3.inventory.CraftMetaItem

I do not get this error when I try to serialize the item in the players hand, I also do not get it when I try to serialize an item in a random Vendor's inventory.

Full error

Log (open) Log (close)

Code:

[16:50:36] [Server thread/ERROR]: Error occurred while disabling ApocalypseZ v1.0 (Is it up to date?)
org.bson.codecs.configuration.CodecConfigurationException: Can't find a codec for class org.bukkit.craftbukkit.v1_16_R3.inventory.CraftMetaItem.
    at org.bson.internal.CodecCache.getOrThrow(CodecCache.java:57) ~[bson-4.1.1.jar:?]
    at org.bson.internal.ProvidersCodecRegistry.get(ProvidersCodecRegistry.java:64) ~[bson-4.1.1.jar:?]
    at org.bson.internal.ChildCodecRegistry.get(ChildCodecRegistry.java:52) ~[bson-4.1.1.jar:?]
    at org.bson.codecs.MapCodec.writeValue(MapCodec.java:174) ~[bson-4.1.1.jar:?]
    at org.bson.codecs.MapCodec.encode(MapCodec.java:113) ~[bson-4.1.1.jar:?]
    at org.bson.codecs.MapCodec.encode(MapCodec.java:40) ~[bson-4.1.1.jar:?]
    at com.mongodb.client.model.BuildersHelper.encodeValue(BuildersHelper.java:37) ~[mongodb-driver-core-4.1.1.jar:?]
    at com.mongodb.client.model.Updates$SimpleUpdate.toBsonDocument(Updates.java:511) ~[mongodb-driver-core-4.1.1.jar:?]
    at com.mongodb.internal.operation.Operations.toBsonDocument(Operations.java:538) ~[mongodb-driver-core-4.1.1.jar:?]
    at com.mongodb.internal.operation.Operations.bulkWrite(Operations.java:400) ~[mongodb-driver-core-4.1.1.jar:?]
    at com.mongodb.internal.operation.Operations.updateOne(Operations.java:337) ~[mongodb-driver-core-4.1.1.jar:?]
    at com.mongodb.internal.operation.SyncOperations.updateOne(SyncOperations.java:181) ~[mongodb-driver-core-4.1.1.jar:?]
    at com.mongodb.client.internal.MongoCollectionImpl.executeUpdate(MongoCollectionImpl.java:994) ~[mongodb-driver-sync-4.1.1.jar:?]
    at com.mongodb.client.internal.MongoCollectionImpl.updateOne(MongoCollectionImpl.java:578) ~[mongodb-driver-sync-4.1.1.jar:?]
    at com.mongodb.client.internal.MongoCollectionImpl.updateOne(MongoCollectionImpl.java:573) ~[mongodb-driver-sync-4.1.1.jar:?]
    at eu.ladeira.apocalypse.Database.saveVendors(Database.java:300) ~[?:?]
    at eu.ladeira.apocalypse.Vendor.unloadVendors(Vendor.java:102) ~[?:?]
    at eu.ladeira.apocalypse.ApocalypseZ.onDisable(ApocalypseZ.java:117) ~[?:?]
    at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:265) ~[spigot-1.16.4.jar:git-Spigot-a19903d-5b74714]
    at org.bukkit.plugin.java.JavaPluginLoader.disablePlugin(JavaPluginLoader.java:376) ~[spigot-1.16.4.jar:git-Spigot-a19903d-5b74714]
    at org.bukkit.plugin.SimplePluginManager.disablePlugin(SimplePluginManager.java:501) ~[spigot-1.16.4.jar:git-Spigot-a19903d-5b74714]
    at org.bukkit.plugin.SimplePluginManager.disablePlugins(SimplePluginManager.java:493) ~[spigot-1.16.4.jar:git-Spigot-a19903d-5b74714]
    at org.bukkit.craftbukkit.v1_16_R3.CraftServer.disablePlugins(CraftServer.java:428) ~[spigot-1.16.4.jar:git-Spigot-a19903d-5b74714]
    at net.minecraft.server.v1_16_R3.MinecraftServer.stop(MinecraftServer.java:716) ~[spigot-1.16.4.jar:git-Spigot-a19903d-5b74714]
    at net.minecraft.server.v1_16_R3.DedicatedServer.stop(DedicatedServer.java:650) ~[spigot-1.16.4.jar:git-Spigot-a19903d-5b74714]
    at net.minecraft.server.v1_16_R3.MinecraftServer.w(MinecraftServer.java:888) ~[spigot-1.16.4.jar:git-Spigot-a19903d-5b74714]
    at net.minecraft.server.v1_16_R3.MinecraftServer.lambda$0(MinecraftServer.java:164) ~[spigot-1.16.4.jar:git-Spigot-a19903d-5b74714]
    at java.lang.Thread.run(Unknown Source) [?:1.8.0_271]

The relevant methods from my classes:

Database (open) Database (close)

Code:

public static void saveVendors(Server serverType, ArrayList<Vendor> vendors) {
        for (Vendor vendor : vendors) {
            ItemStack[] items = vendor.getInventory().getContents();
            for (int i = 0; i < items.length; i++) {
                if (items[i] != null) {
                    servers.updateOne(eq("server", serverType.toString()), set("vendors." + vendor.getName() + "." + i, items[i].serialize()));
                } else {
                    servers.updateOne(eq("server", serverType.toString()), set("vendors." + vendor.getName() + "." + i, "empty"));
                }
            }
        }
    }

(The Vendor.unloadVendors() just gets a list of vendors and calls the saveVendors() method, I know that is not the problem)
(Vendor is a custom player that extends the EntityPlayer class)

SOLVED

The issue was not with bukkit itself but was with the way I saved the ItemStack to the MongoDB Java Driver. I had to use POJOs (Plain Old Java Objects) to save the serialized itemstack.

How I fixed it:

MongoDB information (open) MongoDB information (close)

When constructing your MongoClientSettings add this piece of code:

Code:

CodecRegistry pojoCodecRegistry = fromRegistries(MongoClientSettings.getDefaultCodecRegistry(), fromProviders(PojoCodecProvider.builder().automatic(true).build()));

and in your MongoClientSettings builder add

Code:

.codecRegistry(pojoCodecRegistry)

so the final version of the MongoClientSettings builder would look something like this (yours will look different)

Code:

MongoClientSettings settings = MongoClientSettings.builder()
                .credential(MongoCredential.createScramSha256Credential(username, auth_database, password.toCharArray()))
                .applyToClusterSettings(builder -> 
                    builder.hosts(Arrays.asList(new ServerAddress(hostname, port))))
                .codecRegistry(pojoCodecRegistry)
                .build();

Essentially what this does, is implement a codec registry, that: "The codec registry will automatically try to create a POJO Codec for unknown classes" see more: MongoDB Java Driver Documentation

The reason you need this, is when you serialize the ItemStack, it saves it as a HashMap<String, Object> and by default MongoDB does not know what to do with Object, but when you implement the codec, it tells MongoDB to just make a Plain Old Java Object (hence POJO).

More about POJOs
Thread on StackOverflow about POJOs

EDIT by Moderator: merged posts, please use the edit button instead of double posting.