LiLaC is discontinued
LiLaC aimed to provide a common API for different Minecraft versions, helping OptiGUI supporting multiple versions of the game. However, it became a relatively big and complex codebase, which is very prone to bugs and oversights. Other than that, I lost interest in maintaining it. OptiGUI will continue to receive updates and additions, but without LiLaC, and only for recent versions of the game.