Select without "All" default

[listvin]

I want my Select input to be selection only from list with following code:

return <Select
        mandatory={true}
        options={["a","b"]}
        name={"ab"}
        label={"choose a or b"}
/>

But I am getting selection from All, a and b. I expect mandatory flag to prevent "All" or similar things to be available.

I noticed that if I supply "xx" to placeholder user gets options xx, a and b. However from code perspective I see values "","a","b". Supplying initialValue does not help -- user can still switch to placeholder value (from his perspective and "" from code perspective)

Am I missing something?

Thank you