Assertion test for adding Context ID.

Author: misselvexu

tests/server-common/src/test/java/io/a2a/server/apps/common/AbstractA2AServerTest.java

@@ -169,6 +169,7 @@ public void testCancelTaskSuccess() throws Exception {
             assertNull(response.getError());
             Task task = response.getResult();
             assertEquals(CANCEL_TASK.getId(), task.getId());
+            assertEquals(CANCEL_TASK.getContextId(), task.getContextId());
             assertEquals(TaskState.CANCELED, task.getStatus().state());
         } catch (A2AServerException e) {
             fail("Unexpected exception during cancel task success test: " + e.getMessage(), e);
@@ -1130,4 +1131,4 @@ protected void savePushNotificationConfigInStore(String taskId, PushNotification
             throw new RuntimeException(response.statusCode() + ": Creating task push notification config failed! " + response.body());
         }
     }
-}
+}