When are harmony exports generated by Webpack?

Question

I have an angular config that output that outputs among others :

__webpack_require__.r(__webpack_exports__);
/* harmony export */ __webpack_require__.d(__webpack_exports__, {
/* harmony export */   Immer: () => (/* binding */ Immer2),
/* harmony export */   applyPatches: () => (/* binding */ applyPatches),
/* harmony export */   castDraft: () => (/* binding */ castDraft),
/* harmony export */   castImmutable: () => (/* binding */ castImmutable),
/* harmony export */   createDraft: () => (/* binding */ createDraft),
/* harmony export */   current: () => (/* binding */ current),
/* harmony export */   enableMapSet: () => (/* binding */ enableMapSet),
/* harmony export */   enablePatches: () => (/* binding */ enablePatches),
/* harmony export */   finishDraft: () => (/* binding */ finishDraft),
/* harmony export */   freeze: () => (/* binding */ freeze),
/* harmony export */   immerable: () => (/* binding */ DRAFTABLE),
/* harmony export */   isDraft: () => (/* binding */ isDraft),
/* harmony export */   isDraftable: () => (/* binding */ isDraftable),
/* harmony export */   nothing: () => (/* binding */ NOTHING),
/* harmony export */   original: () => (/* binding */ original),
/* harmony export */   produce: () => (/* binding */ produce),
/* harmony export */   produceWithPatches: () => (/* binding */ produceWithPatches),
/* harmony export */   setAutoFreeze: () => (/* binding */ setAutoFreeze),
/* harmony export */   setUseStrictShallowCopy: () => (/* binding */ setUseStrictShallowCopy)
/* harmony export */ });

This is the export from the library immer.

I'm trying to reproduce that part with the harmony exports but without any luck.

Stackblitz repro.

When does webpack produce these kind of output (the harmony exports) ? Can you help me achieve something similar on the stackblitz ?