code: @Override
      public DbxAuthFinish finishFromRedirect(String redirectUri,
                                              DbxSessionStore sessionStore,
                                              Map<String, String[]> params)
          throws DbxException, BadRequestException, BadStateException, CsrfException,
          NotApprovedException, ProviderException {
          return super.finishFromRedirect(redirectUri, sessionStore, params);
      }
docs: Call this after the user has visited the authorizaton URL and Dropbox has redirected them
  back to your native app, with the same {@link DbxPKCEWebAuth} instancd that generated
  the authorization URL.
  
  @throws BadRequestException If the redirect request is missing required query parameters,
  contains duplicate parameters, or includes mutually exclusive parameters (e.g. {@code
  "error"} and {@code "code"}).
  @throws BadStateException If the CSRF token retrieved from {@code sessionStore} is {@code
  null} or malformed.
  @throws CsrfException If the CSRF token passed in {@code params} does not match the CSRF
  token from {@code sessionStore}. This implies the redirect request may be forged.
  @throws NotApprovedException If the user chose to deny the authorization request.
  @throws ProviderException If an OAuth2 error response besides {@code "access_denied"} is
  set.
  @throws DbxException if the instance is not the same one used to generate authorization
  URL, or if an error occurs communicating with Dropbox.