Time zone: Host. What does that mean?

Question

I know that there is several ways to setup system timezone on CentOS host. What I would like to know is the meaning of this Host timezone which seems to be set by default and is reported by timedatectl utility

$timedatectl

      Local time: Tue 2019-04-02 13:13:25 CEST
  Universal time: Tue 2019-04-02 11:13:25 UTC
        RTC time: n/a
       Time zone: Host (CEST, +0200)
     NTP enabled: n/a
NTP synchronized: yes
 RTC in local TZ: no
      DST active: yes
 Last DST change: DST began at
                  Sun 2019-03-31 01:59:59 CET
                  Sun 2019-03-31 03:00:00 CEST
 Next DST change: DST ends (the clock jumps one hour backwards) at
                  Sun 2019-10-27 02:59:59 CEST
                  Sun 2019-10-27 02:00:00 CET

This Host timezone setting does not seem good enough for particularly java applications when I do define system timezeone to more meaningfull Country/City setting, like this:

$ timedatectl 
      Local time: Tue 2019-04-02 13:32:05 CEST
  Universal time: Tue 2019-04-02 11:32:05 UTC
        RTC time: Tue 2019-04-02 13:32:05
       Time zone: Europe/Amsterdam (CEST, +0200)
    ....

that is used by JVM by setting its user.timezone system property to the same Country/City. If however the Host timezone setting is in effect, JVM does ignore this completely and sets user.timezone to GMT+01:00 which differs from Host (CEST, +0200) and confuses me. Summarizing above

1. What is the meaning of the timezone named Host?
2. Why it is not respected by JVM
3. Once I change timezone to some Country/City, is there a way to reset it back to Host (if that makes sense at all)?

Answer 1

Personally I have never see that "host" value, do you have this entry when you type:

timedatectl list-timezones | grep -i host

I think no because the only value that not have country/city is "UTC". And why you don't just use Europe/Amsterdam TZ , it's also in CEST and +2h00 GMT.