fix Cf04:等待更慢的任务结束再退出,避免JVM退出打断线程

src/main/java/space/anyi/Cf04_ThenEither.java

@@ -28,6 +28,7 @@ public class Cf04_ThenEither {
         CompletableFuture<Void> r1 = CompletableFuture.runAsync(() -> sleep(60));
         CompletableFuture<Void> r2 = CompletableFuture.runAsync(() -> sleep(500));
         r1.runAfterEither(r2, () -> System.out.println("runAfterEither: 有一路先完成了")).join();
+        r2.join();   // 等待较慢的一路也结束，避免 main 退出时打断它
     }
 
     private static void sleep(long ms) {