Fix incorrect generic type passed to MessageBodyWriter#writeTo

Fixes: #31818
(cherry picked from commit 5221dac)

Author: geoand

independent-projects/resteasy-reactive/server/runtime/src/main/java/org/jboss/resteasy/reactive/server/core/ServerSerialisers.java

@@ -198,16 +198,19 @@ public static boolean invokeWriter(ResteasyReactiveRequestContext context, Objec
         WriterInterceptor[] writerInterceptors = context.getWriterInterceptors();
         boolean outputStreamSet = context.getOutputStream() != null;
         context.serverResponse().setPreCommitListener(HEADER_FUNCTION);
+
+        RuntimeResource target = context.getTarget();
+        Type genericType;
+        if (context.hasGenericReturnType()) { // make sure that when a Response with a GenericEntity was returned, we use it
+            genericType = context.getGenericReturnType();
+        } else {
+            genericType = target == null ? null : target.getReturnType();
+        }
+
         try {
             if (writer instanceof ServerMessageBodyWriter && writerInterceptors == null && !outputStreamSet) {
                 ServerMessageBodyWriter<Object> quarkusRestWriter = (ServerMessageBodyWriter<Object>) writer;
-                RuntimeResource target = context.getTarget();
-                Type genericType;
-                if (context.hasGenericReturnType()) { // make sure that when a Response with a GenericEntity was returned, we use it
-                    genericType = context.getGenericReturnType();
-                } else {
-                    genericType = target == null ? null : target.getReturnType();
-                }
+
                 Class<?> entityClass = entity.getClass();
                 if (quarkusRestWriter.isWriteable(
                         entityClass,
@@ -230,7 +233,7 @@ public static boolean invokeWriter(ResteasyReactiveRequestContext context, Objec
                         context.setResponseContentType(mediaType);
                     }
                     if (writerInterceptors == null) {
-                        writer.writeTo(entity, entity.getClass(), context.getGenericReturnType(),
+                        writer.writeTo(entity, entity.getClass(), genericType,
                                 context.getAllAnnotations(), context.getResponseMediaType(), response.getHeaders(),
                                 context.getOrCreateOutputStream());
                         context.getOrCreateOutputStream().close();

independent-projects/resteasy-reactive/server/vertx/src/test/java/org/jboss/resteasy/reactive/server/vertx/test/simple/SimpleQuarkusRestResource.java

@@ -233,6 +233,12 @@ public TestClass writer() {
         return new TestClass();
     }
 
+    @GET
+    @Path("uni-writer")
+    public Uni<TestClass> uniWriter() {
+        return Uni.createFrom().item(new TestClass());
+    }
+
     @GET
     @Path("fast-writer")
     @Produces("text/plain")

independent-projects/resteasy-reactive/server/vertx/src/test/java/org/jboss/resteasy/reactive/server/vertx/test/simple/SimpleQuarkusRestTestCase.java

@@ -206,6 +206,8 @@ public void testWriter() {
                 .then().body(Matchers.equalTo("OK"));
         RestAssured.get("/simple/writer")
                 .then().body(Matchers.equalTo("WRITER"));
+        RestAssured.get("/simple/uni-writer")
+                .then().body(Matchers.equalTo("WRITER"));
 
         RestAssured.get("/simple/fast-writer")
                 .then().body(Matchers.equalTo("OK"));

independent-projects/resteasy-reactive/server/vertx/src/test/java/org/jboss/resteasy/reactive/server/vertx/test/simple/TestWriter.java

@@ -26,7 +26,11 @@ public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotat
     public void writeTo(TestClass t, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType,
             MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream)
             throws IOException, WebApplicationException {
-        entityStream.write("WRITER".getBytes(StandardCharsets.UTF_8));
+        if (genericType.getTypeName().equals(TestClass.class.getName())) {
+            entityStream.write("WRITER".getBytes(StandardCharsets.UTF_8));
+        } else {
+            entityStream.write("INCORRECT GENERIC TYPE".getBytes(StandardCharsets.UTF_8));
+        }
     }
 
 }