killbill-memoizeit

diff --git a/jaxrs/src/main/java/org/killbill/billing/jaxrs/resources/JaxRsResourceBase.java b/jaxrs/src/main/java/org/killbill/billing/jaxrs/resources/JaxRsResourceBase.java
index 2a3da40..afdf828 100644
--- a/jaxrs/src/main/java/org/killbill/billing/jaxrs/resources/JaxRsResourceBase.java
+++ b/jaxrs/src/main/java/org/killbill/billing/jaxrs/resources/JaxRsResourceBase.java
@@ -350,12 +350,11 @@ public abstract class JaxRsResourceBase implements JaxrsResource {
     }
 
     protected void validatePaymentMethodForAccount(final UUID accountId, final UUID paymentMethodId, final CallContext callContext) throws PaymentApiException {
-        if (paymentMethodId == null) {
-            throw new PaymentApiException(ErrorCode.PAYMENT_NO_DEFAULT_PAYMENT_METHOD, accountId);
-        }
-        final PaymentMethod paymentMethod = paymentApi.getPaymentMethodById(paymentMethodId, false, false, ImmutableList.<PluginProperty>of(), callContext);
-        if (!paymentMethod.getAccountId().equals(accountId)) {
-            throw new PaymentApiException(ErrorCode.PAYMENT_NO_SUCH_PAYMENT_METHOD, paymentMethodId);
+        if (paymentMethodId != null) {
+            final PaymentMethod paymentMethod = paymentApi.getPaymentMethodById(paymentMethodId, false, false, ImmutableList.<PluginProperty>of(), callContext);
+            if (!paymentMethod.getAccountId().equals(accountId)) {
+                throw new PaymentApiException(ErrorCode.PAYMENT_NO_SUCH_PAYMENT_METHOD, paymentMethodId);
+            }
         }
     }
 

diff --git a/payment/src/main/java/org/killbill/billing/payment/api/DefaultPaymentApi.java b/payment/src/main/java/org/killbill/billing/payment/api/DefaultPaymentApi.java
index 6174f20..2674a79 100644
--- a/payment/src/main/java/org/killbill/billing/payment/api/DefaultPaymentApi.java
+++ b/payment/src/main/java/org/killbill/billing/payment/api/DefaultPaymentApi.java
@@ -325,17 +325,12 @@ public class DefaultPaymentApi extends DefaultApiBase implements PaymentApi {
         checkNotNullParameter(properties, "plugin properties");
         checkExternalKeyLength(paymentTransactionExternalKey);
 
-        if (paymentMethodId == null && !paymentOptions.isExternalPayment()) {
-            throw new PaymentApiException(ErrorCode.PAYMENT_NO_DEFAULT_PAYMENT_METHOD, "paymentMethodId", "should not be null");
-        }
         final InternalCallContext internalCallContext = internalCallContextFactory.createInternalCallContext(account.getId(), callContext);
 
-        // TODO validate if the code is located properly here
-        // The code should understand that the external payment method needs to be created
-        // if it doesn't exist yet and trigger a CREDIT using the (built-in) external payment plugin.
-        final UUID nonNullPaymentMethodId = (paymentMethodId != null) ?
-                                           paymentMethodId :
-                                           paymentMethodProcessor.createOrGetExternalPaymentMethod(UUIDs.randomUUID().toString(), account, properties, callContext, internalCallContext);
+
+        final UUID resolvedPaymentMethodId = (paymentMethodId == null && paymentOptions.isExternalPayment()) ?
+                                             paymentMethodProcessor.createOrGetExternalPaymentMethod(UUIDs.randomUUID().toString(), account, properties, callContext, internalCallContext) :
+                                             paymentMethodId;
 
         final String transactionType = TransactionType.PURCHASE.name();
         Payment payment = null;
@@ -344,7 +339,7 @@ public class DefaultPaymentApi extends DefaultApiBase implements PaymentApi {
         try {
             logEnterAPICall(log, transactionType, account, paymentMethodId, paymentId, null, amount, currency, paymentExternalKey, paymentTransactionExternalKey, null, paymentControlPluginNames);
 
-            payment = pluginControlPaymentProcessor.createPurchase(IS_API_PAYMENT, account, nonNullPaymentMethodId, paymentId, amount, currency, paymentExternalKey, paymentTransactionExternalKey,
+            payment = pluginControlPaymentProcessor.createPurchase(IS_API_PAYMENT, account, resolvedPaymentMethodId, paymentId, amount, currency, paymentExternalKey, paymentTransactionExternalKey,
                                                                                  properties, paymentControlPluginNames, callContext, internalCallContext);
 
             paymentTransaction = findPaymentTransaction(payment, paymentTransactionExternalKey);