On Debian-based Linux distributions such as Ubuntu, the `/etc/timezone` file was previously used to determine the JDK's default time zone (`TimeZone.getDefault()`). According to [Debian's Wiki](https://wiki.debian.org/TimeZoneChanges#Check_Configured_Timezone), `/etc/localtime` is now the primary source for the system's default time zone, making `/etc/timezone` redundant. As a result, the JDK's default time zone detection logic has been updated to use `/etc/localtime` instead of `/etc/timezone`. If `/etc/localtime` and `/etc/timezone` are inconsistent for any reason, the JDK's default time zone is now determined solely based on `/etc/localtime` file.