For all owners/users of a Viesmann heating system that enlisted to be part of development programm Viesmann did send a mail recently in which they suggested to change th used endpoint from “v1” to “v2”.
This change has been incooperated by the user thetrueavatar (merci beaucoup). A new .phar is published under the name Viessmann-Api-1.4.0.phar in here. Note that you need to change the used name of this .phar in the bootstrap.php !
I posted a solution for the new API: https://community.openhab.org/t/vitoconnect-getting-values-via-the-new-api-by-using-rules/123900