Fixed the behavior of REST-XML and REST-JSON services that respond with no payload.

.changes/next-release/bugfix-AWSSDKforJavav2-985054b.json

@@ -0,0 +1,5 @@
+{
+    "type": "bugfix",
+    "category": "AWS SDK for Java v2",
+    "description": "Fixed an issue where successful JSON service responses were required to include a payload (fixes NullPointerException originating from JsonProtocolUnmarshaller)."
+}

.changes/next-release/bugfix-AWSSDKforJavav2-9917e4a.json

@@ -0,0 +1,5 @@
+{
+    "type": "bugfix",
+    "category": "AWS SDK for Java v2",
+    "description": "Fixed an issue with XML services, where the service responding with no payload would treat the payload as empty. Now, empty payloads will properly be populated within the XML response as \"null\"."
+}

core/protocols/aws-json-protocol/src/main/java/software/amazon/awssdk/protocols/json/internal/unmarshall/JsonProtocolUnmarshaller.java

@@ -164,8 +164,8 @@ public T unmarshall(JsonUnmarshallerContext context,
 
     public <TypeT extends SdkPojo> TypeT unmarshall(SdkPojo sdkPojo,
                             SdkHttpFullResponse response) throws IOException {
-        if (hasPayloadMembersOnUnmarshall(sdkPojo) && !hasExplicitBlobPayloadMember(sdkPojo)) {
-            SdkJsonNode jsonNode = parser.parse(ReleasableInputStream.wrap(response.content().orElse(null)).disableClose());
+        if (hasPayloadMembersOnUnmarshall(sdkPojo) && !hasExplicitBlobPayloadMember(sdkPojo) && response.content().isPresent()) {
+            SdkJsonNode jsonNode = parser.parse(ReleasableInputStream.wrap(response.content().get()).disableClose());
             return unmarshall(sdkPojo, response, jsonNode);
         } else {
             return unmarshall(sdkPojo, response, null);
@@ -204,8 +204,9 @@ private static <TypeT extends SdkPojo> TypeT unmarshallStructured(SdkPojo sdkPoj
                                                                       SdkJsonNode jsonContent,
                                                                       JsonUnmarshallerContext context) {
         for (SdkField<?> field : sdkPojo.sdkFields()) {
-            if (isExplicitPayloadMember(field) && field.marshallingType() == MarshallingType.SDK_BYTES) {
-                field.set(sdkPojo, SdkBytes.fromInputStream(context.response().content().orElse(null)));
+            if (isExplicitPayloadMember(field) && field.marshallingType() == MarshallingType.SDK_BYTES &&
+                context.response().content().isPresent()) {
+                field.set(sdkPojo, SdkBytes.fromInputStream(context.response().content().get()));
             } else {
                 SdkJsonNode jsonFieldContent = getSdkJsonNode(jsonContent, field);
                 JsonUnmarshaller<Object> unmarshaller = context.getUnmarshaller(field.location(), field.marshallingType());

core/protocols/aws-xml-protocol/src/main/java/software/amazon/awssdk/protocols/xml/internal/unmarshall/XmlProtocolUnmarshaller.java

@@ -55,7 +55,6 @@ public static XmlProtocolUnmarshaller create() {
 
     public <TypeT extends SdkPojo> TypeT unmarshall(SdkPojo sdkPojo,
                                                     SdkHttpFullResponse response) {
-
         XmlElement document = XmlResponseParserUtils.parse(sdkPojo, response);
         return unmarshall(sdkPojo, document, response);
     }
@@ -81,6 +80,11 @@ SdkPojo unmarshall(XmlUnmarshallerContext context, SdkPojo sdkPojo, XmlElement r
             XmlUnmarshaller<Object> unmarshaller = REGISTRY.getUnmarshaller(field.location(), field.marshallingType());
 
             if (root != null && field.location() == MarshallLocation.PAYLOAD) {
+                if (!context.response().content().isPresent()) {
+                    // This is a payload field, but the service sent no content. Do not populate this field (leave it null).
+                    continue;
+                }
+
                 if (isAttribute(field)) {
                     root.getOptionalAttributeByName(field.unmarshallLocationName())
                         .ifPresent(e -> field.set(sdkPojo, e));

test/protocol-tests-core/src/main/resources/software/amazon/awssdk/protocol/suites/cases/rest-core-output.json

@@ -86,6 +86,39 @@
           // Empty object
       }
     }
+  },
+  {
+    "description": "Empty payload responses are unmarshalled",
+    "given": {
+      "response": {
+        "status_code": 204
+      }
+    },
+
+    "when": {
+      "action": "unmarshall",
+      "operation": "AllTypes"
+    },
+    "then": {
+      "deserializedAs": {
+      }
+    }
+  },
+  {
+    "description": "Empty payload blob responses are unmarshalled",
+    "given": {
+      "response": {
+        "status_code": 204
+      }
+    },
+    "when": {
+      "action": "unmarshall",
+      "operation": "OperationWithExplicitPayloadBlob"
+    },
+    "then": {
+      "deserializedAs": {
+      }
+    }
   }
   // TODO header maps, service models supports this but Java SDK does not (not currently exercised)
   // TODO header maps with prefix, services models do not support this, only used by S3