Hxcpp how to add const meta to return type?

hxcpp how to add const meta to return type?

@:const is not working.

  int getX() const { return x; }   //how to add const in hxcpp?

  void setX(int x_) { x = x_; }

and haxe code

var _x:Float = 0;

    @:keep

    public var x(get, set):Float;

    function set_x(newX:Float) {

        _x = newX;

        trace('set x wasm=$newX');

        return _x;

    }

    @:const 

    function get_x() {

        return _x;

    }

from emcc

https://emscripten.org/docs/porting/connecting_cpp_and_javascript/embind.html#classes