Fix resource targetting for a stack level hook

Author: brianlaoaws

src/main/java/software/amazon/cloudformation/HookAbstractWrapper.java

@@ -424,7 +424,7 @@ protected boolean isHookInvocationPayloadRemote(HookRequestData hookRequestData)
             throw new TerminalException("No payload data set.");
         }
 
-        return hookRequestData.getTargetModel().isEmpty();
+        return (hookRequestData.getTargetModel() == null || hookRequestData.getTargetModel().isEmpty());
     }
 
     /**

src/test/java/software/amazon/cloudformation/HookLambdaWrapperTest.java

@@ -418,10 +418,13 @@ public void testIsHookInvocationPayloadRemote() {
          HookRequestData onlyPayloadPopulated = HookRequestData.builder()
                  .targetModel(Collections.emptyMap())
                  .payload("http://s3PresignedUrl").build();
+         HookRequestData onlyPayloadPopulatedWithNullTargetModel = HookRequestData.builder().targetModel(null)
+                 .payload("http://s3PresignedUrl").build();
 
          Assertions.assertFalse(wrapper.isHookInvocationPayloadRemote(bothFieldsPopulated));
          Assertions.assertFalse(wrapper.isHookInvocationPayloadRemote(onlyTargetModelPopulated));
          Assertions.assertTrue(wrapper.isHookInvocationPayloadRemote(onlyPayloadPopulated));
+         Assertions.assertTrue(wrapper.isHookInvocationPayloadRemote(onlyPayloadPopulatedWithNullTargetModel));
      }
 
     private final String expectedStringWhenStrictDeserializingWithExtraneousFields = "Unrecognized field \"targetName\" (class software.amazon.cloudformation.proxy.hook.HookInvocationRequest), not marked as ignorable (10 known properties: \"requestContext\", \"stackId\", \"clientRequestToken\", \"hookModel\", \"hookTypeName\", \"requestData\", \"actionInvocationPoint\", \"awsAccountId\", \"changeSetId\", \"hookTypeVersion\"])\n"