From a9816fa0c48c5093241df0f90f19ce4ea4bc7f9a Mon Sep 17 00:00:00 2001
From: Georgios Andrianakis <geoand@gmail.com>
Date: Fri, 11 Mar 2022 06:35:38 +0200
Subject: [PATCH] Support wildcards in generic return types of JAX-RS methods

Fixes: #24250
---
 .../core/startup/RuntimeResourceDeployment.java  | 16 ++++++++++++----
 .../test/response/RestResponseResource.java      |  6 ++++++
 .../vertx/test/response/RestResponseTest.java    |  4 ++++
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/independent-projects/resteasy-reactive/server/runtime/src/main/java/org/jboss/resteasy/reactive/server/core/startup/RuntimeResourceDeployment.java b/independent-projects/resteasy-reactive/server/runtime/src/main/java/org/jboss/resteasy/reactive/server/core/startup/RuntimeResourceDeployment.java
index 174ea7123026e..d8b8aa906779a 100644
--- a/independent-projects/resteasy-reactive/server/runtime/src/main/java/org/jboss/resteasy/reactive/server/core/startup/RuntimeResourceDeployment.java
+++ b/independent-projects/resteasy-reactive/server/runtime/src/main/java/org/jboss/resteasy/reactive/server/core/startup/RuntimeResourceDeployment.java
@@ -8,6 +8,7 @@
 import java.lang.reflect.Method;
 import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
+import java.lang.reflect.WildcardType;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -631,20 +632,27 @@ private Type getEffectiveReturnType(Type returnType) {
             return returnType;
         if (returnType instanceof ParameterizedType) {
             ParameterizedType type = (ParameterizedType) returnType;
+            Type firstTypeArgument = type.getActualTypeArguments()[0];
             if (type.getRawType() == CompletionStage.class) {
-                return getEffectiveReturnType(type.getActualTypeArguments()[0]);
+                return getEffectiveReturnType(firstTypeArgument);
             }
             if (type.getRawType() == Uni.class) {
-                return getEffectiveReturnType(type.getActualTypeArguments()[0]);
+                return getEffectiveReturnType(firstTypeArgument);
             }
             if (type.getRawType() == Multi.class) {
-                return getEffectiveReturnType(type.getActualTypeArguments()[0]);
+                return getEffectiveReturnType(firstTypeArgument);
             }
             if (type.getRawType() == RestResponse.class) {
-                return getEffectiveReturnType(type.getActualTypeArguments()[0]);
+                return getEffectiveReturnType(firstTypeArgument);
             }
             return returnType;
         }
+        if (returnType instanceof WildcardType) {
+            Type[] bounds = ((WildcardType) returnType).getLowerBounds();
+            if (bounds.length > 0)
+                return getRawType(bounds[0]);
+            return getRawType(((WildcardType) returnType).getUpperBounds()[0]);
+        }
         throw new UnsupportedOperationException("Endpoint return type not supported yet: " + returnType);
     }
 
diff --git a/independent-projects/resteasy-reactive/server/vertx/src/test/java/org/jboss/resteasy/reactive/server/vertx/test/response/RestResponseResource.java b/independent-projects/resteasy-reactive/server/vertx/src/test/java/org/jboss/resteasy/reactive/server/vertx/test/response/RestResponseResource.java
index b246794fbcb82..286b0e1be476c 100644
--- a/independent-projects/resteasy-reactive/server/vertx/src/test/java/org/jboss/resteasy/reactive/server/vertx/test/response/RestResponseResource.java
+++ b/independent-projects/resteasy-reactive/server/vertx/src/test/java/org/jboss/resteasy/reactive/server/vertx/test/response/RestResponseResource.java
@@ -26,6 +26,12 @@ public RestResponse<String> getString() {
         return RestResponse.ok("Hello");
     }
 
+    @GET
+    @Path("rest-response-wildcard")
+    public RestResponse<?> wildcard() {
+        return RestResponse.ResponseBuilder.ok("Hello").header("content-type", "text/plain").build();
+    }
+
     @GET
     @Path("rest-response-full")
     public RestResponse<String> getResponse() throws URISyntaxException {
diff --git a/independent-projects/resteasy-reactive/server/vertx/src/test/java/org/jboss/resteasy/reactive/server/vertx/test/response/RestResponseTest.java b/independent-projects/resteasy-reactive/server/vertx/src/test/java/org/jboss/resteasy/reactive/server/vertx/test/response/RestResponseTest.java
index 6113359c1077e..01196ef4b16af 100644
--- a/independent-projects/resteasy-reactive/server/vertx/src/test/java/org/jboss/resteasy/reactive/server/vertx/test/response/RestResponseTest.java
+++ b/independent-projects/resteasy-reactive/server/vertx/src/test/java/org/jboss/resteasy/reactive/server/vertx/test/response/RestResponseTest.java
@@ -27,6 +27,10 @@ public void test() {
                 .then().statusCode(200)
                 .and().body(Matchers.equalTo("Hello"))
                 .and().contentType("text/plain");
+        RestAssured.get("/rest-response-wildcard")
+                .then().statusCode(200)
+                .and().body(Matchers.equalTo("Hello"))
+                .and().contentType("text/plain");
         RestAssured.get("/rest-response-full")
                 .then()
                 .statusCode(200)