Allow default methods in MavenClassloader callbacks

tests/integration-tests-base-groovy/pom.xml

@@ -35,7 +35,6 @@
   <name>Apache BookKeeper :: Tests :: Base module for Arquillian based integration tests using groovy</name>
 
   <properties>
-    <groovy.version>2.4.13</groovy.version>
     <groovy-eclipse-compiler.version>2.9.2-04</groovy-eclipse-compiler.version>
     <groovy-eclipse-batch.version>2.4.13-02</groovy-eclipse-batch.version>
   </properties>

tests/integration-tests-utils/pom.xml

@@ -92,6 +92,12 @@
       <version>${arquillian-cube.version}</version>
     </dependency>
 
+    <dependency>
+      <groupId>org.codehaus.groovy</groupId>
+      <artifactId>groovy-all</artifactId>
+      <version>${groovy.version}</version>
+    </dependency>
+
   </dependencies>
 
   <build>

tests/integration-tests-utils/src/main/java/org/apache/bookkeeper/tests/MavenClassLoader.java

@@ -22,7 +22,11 @@
 
 import com.google.common.collect.Lists;
 
+import groovy.lang.Closure;
+
 import java.io.File;
+import java.lang.invoke.MethodHandles;
+import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.Method;
 import java.lang.reflect.Proxy;
@@ -135,14 +139,25 @@ public Object callStaticMethod(String className, String methodName, ArrayList<?>
         }
     }
 
-    public Object createCallback(String interfaceName, Object closure) throws Exception {
+    public Object createCallback(String interfaceName, Closure closure) throws Exception {
+        final Constructor<MethodHandles.Lookup> constructor = MethodHandles.Lookup.class.getDeclaredConstructor(
+                Class.class, int.class);
+        constructor.setAccessible(true);
         return Proxy.newProxyInstance(classloader,
                                       new Class<?>[]{ Class.forName(interfaceName, true, classloader) },
                                       new InvocationHandler() {
+
                                           @Override
                                           public Object invoke(Object proxy, Method m, Object[] args) throws Throwable {
-                                              Method call = closure.getClass().getMethod("call", Object[].class);
-                                              return call.invoke(closure, (Object)args);
+                                              if (args.length == closure.getMaximumNumberOfParameters()) {
+                                                  return closure.call(args);
+                                              } else {
+                                                  final Class<?> declaringClass = m.getDeclaringClass();
+                                                  return constructor.newInstance(declaringClass, MethodHandles.Lookup.PRIVATE)
+                                                      .unreflectSpecial(m, declaringClass)
+                                                      .bindTo(proxy)
+                                                      .invokeWithArguments(args);
+                                              }
                                           }
                                       });
     }

tests/pom.xml

@@ -27,6 +27,11 @@
   <groupId>org.apache.bookkeeper.tests</groupId>
   <artifactId>tests-parent</artifactId>
   <name>Apache BookKeeper :: Tests</name>
+
+  <properties>
+    <groovy.version>2.4.13</groovy.version>
+  </properties>
+
   <modules>
     <module>shaded</module>
     <module>docker-images</module>