Column modification truncated

I have a table holding emails. I want to change the columns to support utf8mb4. VARCHAR columns succeed, but LONGTEXT does not.

This is the erroneous changeset

• changeSet:
  id: 1574166279666-8
  author: me
  dbms: mysql, mariadb
  changes:

• modifyDataType:
  tableName: event_mail
  columnName: body
  newDataType: LONGBLOB

• modifyDataType:
  tableName: event_mail
  columnName: body
  newDataType: LONGTEXT CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci

column `body` stays at latin1, liquibase gives following log output:
```
2019-11-19 14:27:28.463 INFO 10832 — [ main] liquibase.executor.jvm.JdbcExecutor : ALTER TABLE documentportal.event_mail MODIFY body LONGBLOB
2019-11-19 14:27:28.559 INFO 10832 — [ main] liquibase.changelog.ChangeSet : event_mail.body datatype was changed to LONGBLOB
2019-11-19 14:27:28.560 INFO 10832 — [ main] liquibase.executor.jvm.JdbcExecutor : ALTER TABLE documentportal.event_mail MODIFY body LONGTEXT
2019-11-19 14:27:28.659 INFO 10832 — [ main] liquibase.changelog.ChangeSet : event_mail.body datatype was changed to LONGTEXT CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci
```
The second 'ALTER TABLE'-statement is generated imcompletely, leaving out the charset information.