Messages defined inside arrow functions are not pickedup

Messages which are defined using defineMessages inside arrow functions are not extracted.

const sample = () => {
const sampleMessage = defineMessage ({
title: {
id: "sample.id",
defaultMessage: "sample.message"
}
});

[BANG88]

The usage looks really strange. Can you tell me what do you want ? I think most use case are just define some messages and use it directly.