minor refactor: avoid two jupiter warnings

Author: paulk-asert

src/test/groovy/bugs/MethodDispatchBug.groovy

@@ -39,7 +39,7 @@ class MethodDispatchBug {
     }
 
     @Test
-    def testBug() {
+    void testBug() {
         def o = this;
 
         assert "BB" == o.doit(true, true);

src/test/groovy/groovy/ClassTest.groovy

@@ -40,8 +40,8 @@ class ClassTest {
     }
 
     @Test
-    def testClassesHaveSuperModiferSet() {
+    void testClassesHaveSuperModiferSet() {
         assert java.lang.reflect.Modifier.isSynchronized(this.class.modifiers)
     }
 
-}
+}