[Feature Request] Required nullable arguments

When calling Java methods from Kahlua, the number of arguments is used to determine the appropriate implementation to call. Because of this, arguments that can be nil are required in the function call for appropriate resolution. This is usually not a concern in Lua, but it could be.

In this example, both f() and f(nil) are appropriate, since the value of x defaults to nil.

---@param x integer?
local function f(x) end

In this example, however, the behaviors of t.f() and t.f(nil) are not equivalent.
(Admittedly, this is a contrived example. Nonetheless, it shows that this would not only be useful for strange cases like Kahlua's implementation.)

---@class Example
---@field f fun(x: integer?)
t = {
    f = function(...)
        assert(select('#', ...) == 1)
    end
}

I don't feel strongly about the annotation that would be used to specify this, but ! comes to mind:

---@class Example
---@field f fun(x: integer?!)
t = {
    f = function(...)
        assert(select('#', ...) == 1)
    end
}

The ?!/!? pair may be redundant, since non-nil argument types are always required. It would also be feasible to represent required but nil-able arguments with ! alone.

未指定任何 repository 文件或测试。首先定位与 Lua 函数和 Java/Kahlua 调用相关的注解处理路径以及参数数量解析路径。比较提议的 ?!、!? 和 ! 形式，然后定义对省略参数与显式 nil 参数的覆盖范围，并在实现前确认预期的语法。