locations = arrayOf("classpath:db/migration") doesn't work

flyway {
    ...
    locations = arrayOf("classpath:db/migration")
    baselineOnMigrate = true
}

I suppose using classpath:db/migration, to indicate the location of migration scripts, should work fine. But it doesn't. I can only use filesystem like below.

flyway {
    ...
    // locations = arrayOf("classpath:db/migration")
    locations = arrayOf("filesystem:src/main/resources/db/migration")
    baselineOnMigrate = true
}

I couldn't find this issue reported in the issued history. I also made sure the folder is not db.migration, but is really src/main/resources/db/migration. Not a very serious issue since I can still use filesystem, but I thought I might as well report it. By the way, I am using the latest version 11.8.0. Here is the folder structure just for reference: