code: @Nullable
      public PaymentMethod createPaymentMethodSynchronous(
              @NonNull PaymentMethodCreateParams paymentMethodCreateParams,
              @NonNull String publishableKey)
              throws AuthenticationException, InvalidRequestException, APIConnectionException,
              APIException {
          return mApiHandler.createPaymentMethod(paymentMethodCreateParams,
                  publishableKey, mStripeAccount);
      }
docs: Blocking method to create a {@link PaymentMethod} object.
  Do not call this on the UI thread or your app will crash.
  
  @param paymentMethodCreateParams params with which to create the PaymentMethod
  @param publishableKey a publishable API key to use
  @return a {@link PaymentMethod} or {@code null} if a problem occurred
  
  @throws AuthenticationException
  @throws InvalidRequestException
  @throws APIConnectionException
  @throws APIException