[Bug] - Required to create apiContext every-time for createPayment

[ryukato]

APIContext has requestId, which needs to guarantee idempotency, so it has be identical for every payment.
I guess we has to create new APIContext when create a payment like below.

private fun createApiContext(): APIContext {
	val context = APIContext(oAuthTokenCredential.getAccessToken(), UUID.randomUUID().toString());
	context.setConfigurationMap(paypalSdkConfigMap);
	return context;
}

please refer to paypal-request-id