I'm using p4 plugin for several months in freestyle jobs, and I'm moving to 'pipelines' implementation (workflow if you like)

According to this documentation, there are some known limitations :
https://github.com/jenkinsci/p4-plugin/blob/master/SETUP.md

especially :

No access to Environment ${VAR} variables

On the other hand, one line below is written :

Exposed Variables :

• P4_CHANGELIST - current changelist (valid for this to be blank when there are no changes).

Within my pipelines, what I see is that 'P4_CHANGELIST' is not available after a call to p4sync.

Is it expected ?

If so, how do I retrieve the changelist at which the sync is done ? (in order to propagate it to further steps and stages in the pipeline)