I would like to ask, how to change in Kendo Grid component column filterable input (see image below) into dropdown menu with two given values (CZ and EN)?

Many thanks for any help.
EDIT:
I tried to do by this way, but with no effect:
{
field :"language",
title : $translate.instant('LANG'),
type: "string",
width:220,
filterable: {
ui: function (element) {
element.kendoDropDownList({
dataSource: ['CZ','EN'],
optionLabel: "--Select Value--"
});
}
}
},
