Adding support for default Methods in the Proxy Target

Modified the `GuardMethodHandler` to correctly wrap any `default` methods available
on a `Target` interface.

feignx-core/src/main/java/feign/proxy/GuardMethodHandler.java

@@ -29,21 +29,22 @@ public class GuardMethodHandler implements TargetMethodHandler {
    * @param target instance this method is for.
    */
   @SuppressWarnings("JavaReflectionMemberAccess")
-  public GuardMethodHandler(Method method, Target<?> target) {
+  public GuardMethodHandler(Method method, Target<?> target, Object proxy) {
     Assert.isNotNull(method, "method is required.");
     Assert.isNotNull(target, "target is required.");
     try {
       /* attempt to create a new instance of the target type */
       Class<?> targetType = target.type();
-      Constructor<Lookup> constructor = Lookup.class.getConstructor(Class.class);
+      Constructor<Lookup> constructor = Lookup.class.getDeclaredConstructor(Class.class);
 
       /* this is the line that breaks on JDK 9+, it violates the new security rules */
       constructor.setAccessible(true);
 
       /* create a temporary instance of the target and execute the method */
       this.guardMethodHandle = constructor.newInstance(targetType)
           .in(targetType)
-          .unreflectSpecial(method, targetType);
+          .unreflectSpecial(method, targetType)
+          .bindTo(proxy);
     } catch (InstantiationException | InvocationTargetException | NoSuchMethodException
         | IllegalAccessException ie) {
       /* either the type does not expose a type that can be instantiated or
@@ -53,26 +54,6 @@ public GuardMethodHandler(Method method, Target<?> target) {
     }
   }
 
-  /**
-   * Bind the HttpMethod Handler to the proxy.
-   *
-   * @param proxy to bind to.
-   */
-  GuardMethodHandler bind(Object proxy) {
-    this.guardMethodHandle.bindTo(proxy);
-    this.bound = true;
-    return this;
-  }
-
-  /**
-   * If this HttpMethod Handler has been bound to a proxy.
-   *
-   * @return {@literal true} if this method handler is already bound, {@literal false} otherwise.
-   */
-  boolean isBound() {
-    return this.bound;
-  }
-
   /**
    * Execute the HttpMethod Handler.
    *

feignx-core/src/main/java/feign/proxy/ProxyTarget.java

@@ -77,7 +77,7 @@ public Object invoke(Object proxy, Method method, Object[] args) throws Throwabl
       /* default, static and non-annotated methods will not be in the map */
       if (method.isDefault()) {
         /* create the handler */
-        methodHandler = this.createGuardMethodHandler(method, this);
+        methodHandler = this.createGuardMethodHandler(method, proxy);
 
         /* add it to the map for later use */
         this.methodHandlerMap.put(method, methodHandler);
@@ -118,13 +118,8 @@ private void buildMethodHandlerMap(Target<?> target, Collection<TargetMethodDefi
   }
 
   private TargetMethodHandler createGuardMethodHandler(Method method, Object proxy) {
-    TargetMethodHandler methodHandler;
-
     /* create a new Guard HttpMethod Handler and register it to the map */
-    methodHandler = new GuardMethodHandler(method, this)
-        .bind(proxy);
-
-    return methodHandler;
+    return new GuardMethodHandler(method, this, proxy);
   }
 
   @Override

feignx-core/src/test/java/feign/FeignTests.java

@@ -3,7 +3,6 @@
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
-import feign.FeignTests.GitHub.Repository;
 import feign.contract.Header;
 import feign.contract.Headers;
 import feign.contract.Param;
@@ -24,17 +23,24 @@ void createTarget_andExecuteRequest() {
   }
 
   @Test
-  void throwUnsupportedOperationException_whenMethodIsNotRegistered() {
+  void defaultMethods_areNotManaged() {
+    GitHub gitHub = Feign.builder()
+        .target(GitHub.class, "https://api.github.com");
+    String owner = gitHub.getOwner();
+    assertThat(owner).isEqualTo("owner");
+  }
+
+  @Test
+  void throwUnsupportedOperationException_whenMethodIsNotRegisteredAndNotDefault() {
     GitHub gitHub = Feign.builder()
         .target(GitHub.class, "https://api.github.com");
 
     /* the get repositories method is not annotated, thus not registered */
     assertThrows(UnsupportedOperationException.class,
         gitHub::getContributors);
-
   }
 
-  @Request("https://api.github.com")
+
   interface GitHub {
 
     @Request("/users/{owner}/repos")
@@ -43,6 +49,10 @@ interface GitHub {
 
     List<String> getContributors();
 
+    default String getOwner() {
+      return "owner";
+    }
+
     class Repository {
 
       private String name;