Importing root requires storage restart

[hg-ms]

Importing a root into a new storage requires the storage to be restarted. Otherwise the storage root stays null.

Steps to reproduce:

1. create or start a storage with a non-null root element
2. export the storage data using one.microstream.storage.types.StorageConnection.exportTypes
3. start a new, empty storage
4. import the previously imported data (don’t forget to copy/ update the type Dictionary) one.microstream.storage.types.StorageConnection.importFiles
5. query the storage root, it will be null Object importedRoot = storage.root()
6. restart the import storage, query root again, it is no more null