code: private static String checkImageStorage(URI sharedImage, URI sharedEdits) {
      if (sharedImage.getScheme().equals(NNStorage.LOCAL_URI_SCHEME)) {
        // shared image is stored in file storage
        return "";
      } else if (sharedImage.getScheme().equals(
          QuorumJournalManager.QJM_URI_SCHEME)
          && sharedImage.equals(sharedEdits)) {
        // image is stored in qjm together with edits
        return "";
      }
      return "Shared image uri: " + sharedImage + " must be either file storage"
          + " or be equal to shared edits storage " + sharedEdits + ". ";
    }
docs: Shared image needs to be in file storage, or QJM providing that QJM also
  stores edits.