fix: event parsing iterator

The EventParsingIterator implementation does not parse correctly events when their payload do not have the eventpayload property set. The current behavior is that if said property "eventpayload" is not present then it fallback to extracting the value from the headers, but this is not a reliable method for parsing event streams since seems that not all services uses this pattern to provide the events. One example is the InvokeModelWithResponseStream operation from bedrock-runtime service. To fix this we check if the event key is set in the headers, and if so then we pick the value from the headers, otherwise we set the event key value based on the event payload.

src/Api/Parser/EventParsingIterator.php

@@ -77,23 +77,23 @@ private function parseEvent(array $event)
         if (empty($event['headers'][':event-type'])) {
             throw new ParserException('Failed to parse without event type.');
         }
-        $eventShape = $this->shape->getMember($event['headers'][':event-type']);
 
+        $eventShape = $this->shape->getMember($event['headers'][':event-type']);
         $parsedEvent = [];
         foreach ($eventShape['members'] as $shape => $details) {
-            if (!empty($details['eventpayload'])) {
-                $payloadShape = $eventShape->getMember($shape);
-                if ($payloadShape['type'] === 'blob') {
-                    $parsedEvent[$shape] = $event['payload'];
-                } else {
+            if (isset($event['headers'][$shape])) {
+                $parsedEvent[$shape] = $event['headers'][$shape];
+            } else {
+                $memberShape = $eventShape->getMember($shape);
+                if ($memberShape instanceof StructureShape) {
                     $parsedEvent[$shape] = $this->parser->parseMemberFromStream(
                         $event['payload'],
-                        $payloadShape,
+                        $memberShape,
                         null
                     );
+                } else {
+                    $parsedEvent[$shape] = $event['payload'];
                 }
-            } else {
-                $parsedEvent[$shape] = $event['headers'][$shape];
             }
         }
 
@@ -109,4 +109,4 @@ private function parseError(array $event)
             $event['headers'][':error-message']
         );
     }
-}
+}