Here's an example of one place where lsp-format.nvim is using . style to invoke a lsp helper: https://github.com/lukas-reineke/lsp-format.nvim/blob/v2.7.1/lua/lsp-format/init.lua#L260.

This was recently deprecated. See:

• neovim/neovim@454ae67
• https://github.com/neovim/neovim/blob/43d552c56648bc3125c7509b3d708b6bf6c0c09c/runtime/doc/deprecated.txt#L48-L55