Expand Attachment system capabilities

[robotgryphon]

This PR lays the foundation to allow for the expansion of the attachment system to new types, without bringing along some of the hard-coded sync and data persistence code that the existing system built due to its few type requirements.

Some examples, with vanilla attachment holders. These expose the holder, data storage, data persistence, and sync systems to anyone that wishes to interact with them, via the capability system:

Usage

public static void registerVanillaAttachmentHosts(RegisterCapabilitiesEvent event) {
        event.registerAttachment(MinecraftServer.class, AttachmentCapabilities.ATTACHMENT_HOLDER, s -> s);
        event.registerAttachment(MinecraftServer.class, AttachmentCapabilities.DATA_STORAGE, s -> s);
        event.registerAttachment(MinecraftServer.class, AttachmentCapabilities.PERSISTENCE, IAttachmentHolder::attachmentPersistenceHandler);
        event.registerAttachment(MinecraftServer.class, AttachmentCapabilities.SYNC, IAttachmentHolder::attachmentSyncHandler);

        event.registerAttachment(ServerLevel.class, AttachmentCapabilities.ATTACHMENT_HOLDER, s -> s);
        event.registerAttachment(ServerLevel.class, AttachmentCapabilities.DATA_STORAGE, s -> s);
        event.registerAttachment(ServerLevel.class, AttachmentCapabilities.PERSISTENCE, IAttachmentHolder::attachmentPersistenceHandler);
        event.registerAttachment(ServerLevel.class, AttachmentCapabilities.SYNC, IAttachmentHolder::attachmentSyncHandler);
    }

Note that this is NOT required for the new sync and persistence code. It simply highlights what is now possible due to the systems moving to common, reusable interfaces.

TODOs

• Finish off the attachment sync handlers registry and client-side data retrieval (Packet Listener + AttachmentHolderSyncHandler classes)
• Reimplement sync game tests in a more composed manner, rather than an all-in-one megatest
• Prove system by demoing attachments and persistence with MinecraftServer and ClientLevel classes
• Documentation
• Cleanup

[neoforged-pr-publishing]

• Publish PR to GitHub Packages

Last commit published: 4f0e1667bc60ddea2b23aa625889644d8af9ee7d - version: 26.1.2.44-beta-pr-3095-server-attachments

PR Publishing

The artifacts published by this PR:

• 📦 net.neoforged:neoforge:26.1.2.44-beta-pr-3095-server-attachments
• 📦 net.neoforged:testframework:26.1.2.44-beta-pr-3095-server-attachments

Repository Declaration

In order to use the artifacts published by the PR, add the following repository to your buildscript:

repositories {
    maven {
        name = "Maven for PR #3095" // https://github.com/neoforged/NeoForge/pull/3095
        url = uri("https://prmaven.neoforged.net/NeoForge/pr3095")
        content {
            includeModule("net.neoforged", "neoforge")
            includeModule("net.neoforged", "testframework")
        }
    }
}

MDK installation

In order to setup a MDK using the latest PR version, run the following commands in a terminal.
The script works on both *nix and Windows as long as you have the JDK bin folder on the path.
The script will clone the MDK in a folder named NeoForge-pr3095.
On Powershell you will need to remove the -L flag from the curl invocation.

mkdir NeoForge-pr3095
cd NeoForge-pr3095
curl -L https://prmaven.neoforged.net/NeoForge/pr3095/net/neoforged/neoforge/26.1.2.44-beta-pr-3095-server-attachments/mdk-pr3095.zip -o mdk.zip
jar xf mdk.zip
rm mdk.zip || del mdk.zip

To test a production environment, you can download the installer from here.

[neoforged-compatibility-checks]

@robotgryphon, this PR introduces breaking changes.
Fortunately, this project is currently accepting breaking changes, but if they are not intentional, please revert them.
Last checked commit: 4f0e1667bc60ddea2b23aa625889644d8af9ee7d.

Compatibility checks

neoforge (:neoforge)

• net/neoforged/neoforge/network/payload/SyncAttachmentsPayload$Target
  • ❗ API class no longer exists
• net/neoforged/neoforge/network/payload/SyncAttachmentsPayload$LevelTarget
  • ❗ API class no longer exists
• net/minecraft/world/level/chunk/ImposterProtoChunk
  • getAttachmentHolder()Lnet/neoforged/neoforge/attachment/AttachmentHolder$AsField;: ❗ API method was removed
• net/neoforged/neoforge/attachment/LevelAttachmentsSavedData
  • ⚠ API class no longer exists
• net/neoforged/neoforge/attachment/AttachmentSyncHandler
  • ❗ API class no longer exists
• net/neoforged/neoforge/attachment/AttachmentInternals
  • copyChunkAttachmentsOnPromotion(Lnet/minecraft/core/HolderLookup$Provider;Lnet/neoforged/neoforge/attachment/AttachmentHolder$AsField;Lnet/neoforged/neoforge/attachment/AttachmentHolder$AsField;)V: ⚠ API method was removed
• net/neoforged/neoforge/network/payload/SyncAttachmentsPayload$BlockEntityTarget
  • ❗ API class no longer exists
• net/neoforged/neoforge/attachment/AttachmentSync
  • ⚠ API class no longer exists
• net/minecraft/world/level/Level
  • ❗ Class missing superclass of net/neoforged/neoforge/attachment/AttachmentHolder
• net/neoforged/neoforge/network/payload/SyncAttachmentsPayload$ChunkTarget
  • ❗ API class no longer exists
• net/neoforged/neoforge/network/payload/SyncAttachmentsPayload
  • ⚠ API class no longer exists
• net/neoforged/neoforge/network/payload/SyncAttachmentsPayload$EntityTarget
  • ❗ API class no longer exists
• net/minecraft/world/level/chunk/ChunkAccess
  • getAttachmentHolder()Lnet/neoforged/neoforge/attachment/AttachmentHolder$AsField;: ⚠ API method was removed
• net/neoforged/neoforge/attachment/AttachmentType$Builder
  • sync(Lnet/neoforged/neoforge/attachment/AttachmentSyncHandler;)Lnet/neoforged/neoforge/attachment/AttachmentType$Builder;: ❗ API method was removed
• net/neoforged/neoforge/attachment/AttachmentHolder$AsField
  • ❗ API class no longer exists

[Technici4n]

This needs a more general solution such that the attachments can be synced to the client as well (and accessed from there). We brainstormed some sort of SessionData class that could be accessed from any level (including a client level) to that effect, should be findable on Discord somewhere.

[Shadows-of-Fire]

It's in this brainstorming thread