cannot recognize emmy field

I have defined an emmy class role:

---@class role
---@field equipment_mgr equipment_mgr

an emmy class equipment_mgr:

---@class equipment_mgr
local data = {
        role = role, ---@type role
        equipment = orm_equipment, ---@type table<integer, db.Equipment>
}

then add some method to equipment_mgr:

---@type equipment_mgr
local mt = {}
mt.__index = mt

---@return db.Equipment
function mt:get_equipment(uid)
    return self.equipment[uid]
end

Lua Diagnostics cannot recognize the method get_equipment:

while other extension can

Start by reproducing the shown Lua class, field, metatable, and get_equipment method in Lua Diagnostics. Compare its recognition of the method with the other extension mentioned; done means Lua Diagnostics recognizes get_equipment on equipment_mgr without the reported diagnostic.