Verify that Proxy instances have access to annotations' default values

For quick access, the sezpoz library stores lists in
META-INF/annotations/ of classes that have been annotated in a
special way.

To support the use case where the annotations actually changed since
sezpoz stored said lists, sezpoz then creates proxy instances for the
annotations to provide some backwards compatibility: as long as there
are default values for any newly-introduced annotation values,
everything is groovy.

Therefore, let's make sure that proxy instances inherit the
annotations' default values.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

test/Annotations.java

@@ -1,4 +1,6 @@
+import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
 
 import avian.testing.annotations.Color;
 import avian.testing.annotations.Test;
@@ -27,6 +29,7 @@ public class Annotations {
     Method noAnno = Annotations.class.getMethod("noAnnotation");
     expect(noAnno.getAnnotation(Test.class) == null);
     expect(noAnno.getAnnotations().length == 0);
+    testProxyDefaultValue();
   }
 
   @Test("couscous")
@@ -39,4 +42,16 @@ public class Annotations {
   public static void noAnnotation() {
     
   }
+
+  private static void testProxyDefaultValue() {
+    ClassLoader loader = Annotations.class.getClassLoader();
+    InvocationHandler handler = new InvocationHandler() {
+      public Object invoke(Object proxy, Method method, Object... args) {
+        return method.getDefaultValue();
+      }
+    };
+    Test test = (Test)
+      Proxy.newProxyInstance(loader, new Class[] { Test.class }, handler);
+    expect("Hello, world!".equals(test.value()));
+  }
 }

test/avian/testing/annotations/Test.java

@@ -5,5 +5,5 @@ import java.lang.annotation.RetentionPolicy;
 
 @Retention(RetentionPolicy.RUNTIME)
 public @interface Test {
-  public String value();
+  public String value() default "Hello, world!";
 }