Emulator does not restore firebaseStorageDownloadTokens on import

[harveylee]

[REQUIRED] Environment info

firebase-tools: 9.12.0

Platform: Windows 10

[REQUIRED] Test case

import { getStorage, useStorageEmulator, ref, getDownloadURL } from '@firebase/storage'

const storage = getStorage()
useStorageEmulator(storage, '127.0.0.1', 9199)

async function getMyFile () {
  const reference = ref(storage, 'myfile')
  return await getDownloadURL(reference)
}

[REQUIRED] Steps to reproduce

1. Run the emulators (including storage): firebase emulators:start --import data --export-on-exit
2. Upload a test file myfile to Storage using the Emulator UI
3. Call the getMyFile() function from Javascript - works as expected, can fetch the file
4. Ctrl+C to shut down the emulator. myfile is exported to data/
5. Note that data/storage_export/metadata/<bucket>/myfile.json doesn't contain anything in customMetadata or downloadTokens properties? (This seems unexpected)
6. Start the emulators again: firebase emulators:start --import data --export-on-exit
7. Call the getMyFile() function from Javascript - receive error:
   FirebaseError: Firebase Storage: The given file does not have any download URLs. (storage/no-download-url)

[REQUIRED] Expected behavior

Download tokens are exported and imported between emulator runs.

[REQUIRED] Actual behavior

Download tokens are not exported/imported by the storage emulator.

[samtstern]

@harveylee thanks for the clear bug report!

[xSAVIKx]

This is a showstopper for us to use the emulator in tests. It'd be great if #3444 can be merged and released sooner.