Fix binding of SdkPojoSupplier to event stream type header.

Event stream type header values are generated from the member name in the event stream structure, not the structure name of the event itself.  When the member name and the event type mismatch, then unmarshalling of events sent from the service fails.

From the spec: `:event-type: This header’s value, a UTF-8 string, is derived from the event’s member name in the eventstream structure`

Author: adamthom-amzn

.changes/next-release/bugfix-AWSSDKforJavav2-85efae2.json

@@ -0,0 +1,5 @@
+{
+    "category": "AWS SDK for Java v2",
+    "type": "bugfix",
+    "description": "Fix unmarshalling of events when structure member name and shape name mismatch."
+}

codegen/src/main/java/software/amazon/awssdk/codegen/poet/client/specs/JsonProtocolSpec.java

@@ -417,9 +417,9 @@ private void responseHandlersForEventStreaming(OperationModel opModel, TypeName
                  protocolFactory,
                  JsonOperationMetadata.class,
                  ClassName.get(EventStreamTaggedUnionPojoSupplier.class));
-        EventStreamUtils.getEvents(eventStream)
+        EventStreamUtils.getEventMembers(eventStream)
                         .forEach(m -> builder.add(".putSdkPojoSupplier(\"$L\", $T::builder)\n",
-                                                  m.getC2jName(), poetExtensions.getModelClass(m.getC2jName())));
+                                                  m.getC2jName(), poetExtensions.getModelClass(m.getShape().getC2jName())));
         builder.add(".defaultSdkPojoSupplier(() -> $T.UNKNOWN)\n"
                     + ".build());\n", eventStreamBaseClass);
     }

codegen/src/test/resources/software/amazon/awssdk/codegen/poet/client/c2j/json/service-2.json

@@ -404,7 +404,7 @@
         "EventOne": {
           "shape": "EventOne"
         },
-        "EventTwo": {
+        "event-two": {
           "shape": "EventTwo"
         }
       },

codegen/src/test/resources/software/amazon/awssdk/codegen/poet/client/test-async-client-class.java

@@ -259,7 +259,7 @@ public CompletableFuture<Void> eventStreamOperation(EventStreamOperationRequest
             HttpResponseHandler<? extends EventStream> eventResponseHandler = protocolFactory.createResponseHandler(
                     JsonOperationMetadata.builder().isPayloadJson(true).hasStreamingSuccessResponse(false).build(),
                     EventStreamTaggedUnionPojoSupplier.builder().putSdkPojoSupplier("EventOne", EventOne::builder)
-                            .putSdkPojoSupplier("EventTwo", EventTwo::builder).defaultSdkPojoSupplier(() -> EventStream.UNKNOWN)
+                            .putSdkPojoSupplier("event-two", EventTwo::builder).defaultSdkPojoSupplier(() -> EventStream.UNKNOWN)
                             .build());
 
             HttpResponseHandler<AwsServiceException> errorResponseHandler = createErrorResponseHandler(protocolFactory,
@@ -397,7 +397,7 @@ public CompletableFuture<Void> eventStreamOperationWithOnlyOutput(
             HttpResponseHandler<? extends EventStream> eventResponseHandler = protocolFactory.createResponseHandler(
                 JsonOperationMetadata.builder().isPayloadJson(true).hasStreamingSuccessResponse(false).build(),
                 EventStreamTaggedUnionPojoSupplier.builder().putSdkPojoSupplier("EventOne", EventOne::builder)
-                                                  .putSdkPojoSupplier("EventTwo", EventTwo::builder).defaultSdkPojoSupplier(() -> EventStream.UNKNOWN)
+                                                  .putSdkPojoSupplier("event-two", EventTwo::builder).defaultSdkPojoSupplier(() -> EventStream.UNKNOWN)
                                                   .build());
 
             HttpResponseHandler<AwsServiceException> errorResponseHandler = createErrorResponseHandler(protocolFactory,