code: @Nullable
      public Token createAccountTokenSynchronous(@NonNull final AccountParams accountParams)
              throws AuthenticationException,
              InvalidRequestException,
              APIConnectionException,
              APIException {
          return createAccountTokenSynchronous(accountParams, mDefaultPublishableKey);
      }
docs: Blocking method to create a {@link Token} for a Connect Account. Do not call this on the UI
  thread or your app will crash. The method uses the currently set
  {@link #mDefaultPublishableKey}.
  
  @param accountParams params to use for this token.
  @return a {@link Token} that can be used for this account.
  
  @throws AuthenticationException failure to properly authenticate yourself (check your key)
  @throws InvalidRequestException your request has invalid parameters
  @throws APIConnectionException failure to connect to Stripe's API
  @throws APIException any other type of problem (for instance, a temporary issue with
  Stripe's servers)