YAML config timestamp default & to update without specified

I wrote the Liquibase Changelog in db.changelog-master.yaml (default for Spring Boot).
I have only one TIMESTMP column in some table, but not for follow version, or sg.

I define the column like this:

• column:
  name: schedule_date
  type: TIMESTAMP
  constraints:
  nullable: false

Without any default value, or any other constraint.

But the SQL create statement contains the following row:
`schedule_date` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,

I tried the xml configuration, and then the create statement not contained the default and the on update value.