fix testCustomExecutor (#2904)

Author: gudegg

dubbo-common/src/test/java/org/apache/dubbo/common/concurrent/CompletableFutureTaskTest.java

@@ -20,6 +20,8 @@
 import static org.junit.Assert.assertThat;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.times;
 
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CountDownLatch;
@@ -94,6 +96,7 @@ public void testCustomExecutor() {
         CompletableFuture<Integer> completableFuture = CompletableFuture.supplyAsync(() -> {
             return 0;
         });
-        completableFuture.thenRunAsync(mock(Runnable.class), verify(mockedExecutor));
+        completableFuture.thenRunAsync(mock(Runnable.class), mockedExecutor);
+        verify(mockedExecutor, times(1)).execute(any());
     }
 }