ForgeAttachment

First 1.12.2 release: ports the NeoForge 1.21.1 data attachment system to Forge 1.12.2.

• Attachments can be attached to any entity or block entity
• Persisted through NBT, synced through a SimpleNetworkWrapper packet
• copyOnDeath support and a registry for attachment types

首个 1.12.2 版本：把 NeoForge 1.21.1 的数据附件系统移植到 Forge 1.12.2。

• 任意实体与方块实体均可挂载附件
• 通过 NBT 持久化，通过 SimpleNetworkWrapper 包同步
• 支持 copyOnDeath，并提供附件类型注册表