Properly use headers from RestMulti when the multi is empty

extensions/resteasy-reactive/rest-jackson/deployment/src/test/java/io/quarkus/resteasy/reactive/jackson/deployment/test/streams/StreamResource.java

@@ -199,6 +199,19 @@ public Multi<Message> multiNdJson2() {
                 Wrapper::getStatus);
     }
 
+    @Path("restmulti/empty")
+    @GET
+    @Produces(RestMediaType.APPLICATION_JSON)
+    public Multi<Message> restMultiEmptyJson() {
+        return RestMulti.fromUniResponse(
+                Uni.createFrom().item(
+                        () -> new Wrapper(Multi.createFrom().empty(),
+                                new AbstractMap.SimpleEntry<>("foo", "bar"), 222)),
+                Wrapper::getData,
+                Wrapper::getHeaders,
+                Wrapper::getStatus);
+    }
+
     @Path("stream-json/multi")
     @GET
     @Produces(RestMediaType.APPLICATION_STREAM_JSON)

extensions/resteasy-reactive/rest-jackson/deployment/src/test/java/io/quarkus/resteasy/reactive/jackson/deployment/test/streams/StreamTestCase.java

@@ -174,6 +174,14 @@ public void testNdJsonMultiFromMulti2() {
                 .header("foo", "bar");
     }
 
+    @Test
+    public void testRestMultiEmptyJson() {
+        when().get(uri.toString() + "streams/restmulti/empty")
+                .then().statusCode(222)
+                .body(is("[]"))
+                .header("foo", "bar");
+    }
+
     @Test
     public void testStreamJsonMultiFromMulti() {
         when().get(uri.toString() + "streams/stream-json/multi")

independent-projects/resteasy-reactive/server/runtime/src/main/java/org/jboss/resteasy/reactive/server/handlers/PublisherResponseHandler.java

@@ -151,7 +151,7 @@ private List<StreamingResponseCustomizer> determineCustomizers(boolean isFirst)
         @Override
         public void onComplete() {
             if (!hadItem) {
-                StreamingUtil.setHeaders(requestContext, requestContext.serverResponse(), staticCustomizers);
+                StreamingUtil.setHeaders(requestContext, requestContext.serverResponse(), this.determineCustomizers(true));
             }
             if (json) {
                 String postfix = onCompleteText();