Properly return HTTP 406 on invalid Accept header

This is very similar to what we do with the
Content-Type header

Fixes: #34858
(cherry picked from commit 338fe53)

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

@@ -127,10 +127,14 @@ public void handle(ResteasyReactiveRequestContext requestContext) throws Excepti
             if (!accepts.isEmpty()) {
                 boolean hasAtLeastOneMatch = false;
                 for (int i = 0; i < accepts.size(); i++) {
-                    boolean matches = acceptHeaderMatches(target, accepts.get(i));
-                    if (matches) {
-                        hasAtLeastOneMatch = true;
-                        break;
+                    try {
+                        boolean matches = acceptHeaderMatches(target, accepts.get(i));
+                        if (matches) {
+                            hasAtLeastOneMatch = true;
+                            break;
+                        }
+                    } catch (IllegalArgumentException ignored) {
+                        // the provided header was not valid
                     }
                 }
                 if (!hasAtLeastOneMatch) {
@@ -150,16 +154,19 @@ public void handle(ResteasyReactiveRequestContext requestContext) throws Excepti
         }
     }
 
+    /**
+     * @return {@code true} if the provided string matches one of the {@code @Produces} values of the resource method
+     * @throws IllegalArgumentException if the provided string cannot be parsed into a {@link MediaType}
+     */
     private boolean acceptHeaderMatches(RequestMapper.RequestMatch<RuntimeResource> target, String accepts) {
         if ((accepts != null) && !accepts.equals(MediaType.WILDCARD)) {
             int commaIndex = accepts.indexOf(',');
             boolean multipleAcceptsValues = commaIndex >= 0;
             MediaType[] producesMediaTypes = target.value.getProduces().getSortedOriginalMediaTypes();
             if (!multipleAcceptsValues && (producesMediaTypes.length == 1)) {
                 // the point of this branch is to eliminate any list creation or string indexing as none is needed
-                MediaType acceptsMediaType = MediaType.valueOf(accepts.trim());
                 MediaType providedMediaType = producesMediaTypes[0];
-                return providedMediaType.isCompatible(acceptsMediaType);
+                return providedMediaType.isCompatible(toMediaType(accepts.trim()));
             } else if (multipleAcceptsValues && (producesMediaTypes.length == 1)) {
                 // this is fairly common case, so we want it to be as fast as possible
                 // we do that by manually splitting the accepts header and immediately checking

independent-projects/resteasy-reactive/server/vertx/src/test/java/org/jboss/resteasy/reactive/server/vertx/test/mediatype/InvalidAcceptTest.java

@@ -0,0 +1,50 @@
+package org.jboss.resteasy.reactive.server.vertx.test.mediatype;
+
+import static io.restassured.RestAssured.config;
+import static io.restassured.RestAssured.given;
+import static io.restassured.config.EncoderConfig.encoderConfig;
+
+import java.util.function.Supplier;
+
+import jakarta.ws.rs.GET;
+import jakarta.ws.rs.Path;
+import jakarta.ws.rs.Produces;
+
+import org.jboss.resteasy.reactive.server.vertx.test.framework.ResteasyReactiveUnitTest;
+import org.jboss.shrinkwrap.api.ShrinkWrap;
+import org.jboss.shrinkwrap.api.spec.JavaArchive;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.restassured.http.ContentType;
+
+public class InvalidAcceptTest {
+
+    @RegisterExtension
+    static ResteasyReactiveUnitTest test = new ResteasyReactiveUnitTest()
+            .setArchiveProducer(new Supplier<>() {
+                @Override
+                public JavaArchive get() {
+                    return ShrinkWrap.create(JavaArchive.class)
+                            .addClasses(HelloResource.class);
+                }
+            });
+
+    @Test
+    public void test() {
+        given().config(config().encoderConfig(encoderConfig().encodeContentTypeAs("invalid", ContentType.TEXT))).body("dummy")
+                .accept("invalid").get("/hello")
+                .then()
+                .statusCode(406);
+    }
+
+    @Path("hello")
+    public static class HelloResource {
+
+        @Produces("text/plain")
+        @GET
+        public String hello() {
+            return "hello";
+        }
+    }
+}