fix(events): archive construct does not have defaultChild set

packages/@aws-cdk/aws-events/lib/archive.ts

@@ -64,7 +64,7 @@ export class Archive extends Resource {
   constructor(scope: Construct, id: string, props: ArchiveProps) {
     super(scope, id, { physicalName: props.archiveName });
 
-    let archive = new CfnArchive(this, 'Archive', {
+    let archive = new CfnArchive(this, 'Default', {
       sourceArn: props.sourceEventBus.eventBusArn,
       description: props.description,
       eventPattern: renderEventPattern(props.eventPattern),

packages/@aws-cdk/aws-events/test/archive.test.ts

@@ -77,4 +77,20 @@ describe('archive', () => {
       },
     });
   });
+
+  test('should have defined defaultChild', () => {
+    const stack = new Stack();
+
+    const eventBus = new EventBus(stack, 'Bus');
+
+    const archive = new Archive(stack, 'Archive', {
+      sourceEventBus: eventBus,
+      eventPattern: {
+        account: [stack.account],
+      },
+      retention: Duration.days(10),
+    });
+
+    expect(archive.node.defaultChild).toBeDefined();
+  });
 });