How to specify rollback in YAML changelog file?

I can't find in the documentation the right syntax to declare rollback statements using YAML, so I tried the following but it doesn't work.

1. databaseChangeLog:
2.   - changeSet:
3.       id: 1
4.       author: foobar
5.       changes:
6.         - createTable:
7.             tableName: users
8.             columns:
9.               - column:
10.                   name: id
11.                   type: int
12.                   autoIncrement: true
13.                   constraints:
14.                     primaryKey: true
15.                     nullable: false
16.               - column:
17.                   name: name
18.                   type: varchar(50)
19.                   constraints:
20.                     nullable: false
21.               - column:
22.                   name: email
23.                   type: varchar(50)
24.                   constraints:
25.                     nullable: false
26.   - changeSet:
27.       id: 2
28.       author: foobar
29.       changes:
30.         - insert:
31.             tableName: users
32.             columns:
33.               - column:
34.                   name: name
35.                   value: John Brown
36.               - column:
37.                   name: email
38.                   value: john@example.com
39.       rollback:
40.         - sql:
41.             sql: TRUNCATE TABLE users;

When I execute the command

1. liquibase --changeLogFile=input.yaml update

it's allright

1. Liquibase Update Successful

but if I try to rollback

1. liquibase --changeLogFile=input.yaml rollbackCountSql 1

I get an error

1. Liquibase rollbackCountSql Failed: liquibase.exception.RollbackImpossibleException: No inverse to liquibase.change.core.InsertDataChange created

Anyone can help me?
Thank you.