RestClient Reactive: copy method parameter annotations to the generat…

…ed class

This is to allow runtime constructs, such as interceptors, to obtain annotations
on parameters of RestClient methods.

extensions/resteasy-reactive/rest-client-reactive/deployment/src/main/java/io/quarkus/rest/client/reactive/deployment/RestClientReactiveProcessor.java

@@ -467,6 +467,11 @@ void addRestClientBeans(Capabilities capabilities,
                                     && !ResteasyReactiveDotNames.PATH.equals(annotation.name())) {
                                 methodCreator.addAnnotation(annotation);
                             }
+                            if (annotation.target().kind() == AnnotationTarget.Kind.METHOD_PARAMETER) {
+                                // TODO should skip annotations like `@PathParam` / `@RestPath`, probably (?)
+                                short position = annotation.target().asMethodParameter().position();
+                                methodCreator.getParameterAnnotations(position).addAnnotation(annotation);
+                            }
                         }
 
                         ResultHandle result;

extensions/resteasy-reactive/rest-client-reactive/deployment/src/test/java/io/quarkus/rest/client/reactive/intercepted/InterceptedRestClientTest.java

@@ -0,0 +1,97 @@
+package io.quarkus.rest.client.reactive.intercepted;
+
+import static io.quarkus.rest.client.reactive.RestClientTestUtil.setUrlForClass;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+import java.lang.reflect.Parameter;
+
+import jakarta.annotation.Priority;
+import jakarta.inject.Inject;
+import jakarta.interceptor.AroundInvoke;
+import jakarta.interceptor.Interceptor;
+import jakarta.interceptor.InterceptorBinding;
+import jakarta.interceptor.InvocationContext;
+import jakarta.ws.rs.GET;
+import jakarta.ws.rs.Path;
+import jakarta.ws.rs.PathParam;
+
+import org.eclipse.microprofile.rest.client.inject.RegisterRestClient;
+import org.eclipse.microprofile.rest.client.inject.RestClient;
+import org.jboss.shrinkwrap.api.asset.StringAsset;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.test.QuarkusUnitTest;
+
+public class InterceptedRestClientTest {
+    @RegisterExtension
+    static final QuarkusUnitTest TEST = new QuarkusUnitTest()
+            .withApplicationRoot((jar) -> jar
+                    .addClasses(TestEndpoint.class, Client.class, MyAnnotation.class, MyInterceptorBinding.class,
+                            MyInterceptor.class)
+                    .addAsResource(new StringAsset(setUrlForClass(Client.class)), "application.properties"));
+
+    @Inject
+    @RestClient
+    Client client;
+
+    @Test
+    public void testFallbackWasUsed() {
+        assertEquals("skipped", client.hello("test"));
+        assertEquals("pong", client.ping("test"));
+    }
+
+    @Path("/test")
+    public static class TestEndpoint {
+        @GET
+        public String get() {
+            return "pong";
+        }
+    }
+
+    @RegisterRestClient
+    @MyInterceptorBinding
+    public interface Client {
+        @GET
+        @Path("/{path}")
+        String hello(@MyAnnotation("skip") @PathParam("path") String path);
+
+        @GET
+        @Path("/{path}")
+        String ping(@MyAnnotation("don't skip") @PathParam("path") String param);
+    }
+
+    @Target(ElementType.PARAMETER)
+    @Retention(RetentionPolicy.RUNTIME)
+    public @interface MyAnnotation {
+        String value();
+    }
+
+    @Target({ ElementType.TYPE, ElementType.METHOD })
+    @Retention(RetentionPolicy.RUNTIME)
+    @Documented
+    @InterceptorBinding
+    public @interface MyInterceptorBinding {
+    }
+
+    @MyInterceptorBinding
+    @Interceptor
+    @Priority(1)
+    public static class MyInterceptor {
+        @AroundInvoke
+        Object aroundInvoke(InvocationContext ctx) throws Exception {
+            for (Parameter parameter : ctx.getMethod().getParameters()) {
+                MyAnnotation anno = parameter.getAnnotation(MyAnnotation.class);
+                if (anno != null && "skip".equals(anno.value())) {
+                    return "skipped";
+                }
+            }
+            return ctx.proceed();
+        }
+    }
+}