Upgrade of both Bonita (6.4.1) and server OS (Ubuntu 14.04)


Hallo everybody.
I need to upgrade a Bonita 6.4.1 installed on an old 14.04 Ubuntu server. I would like to get some advice on what would be the best way to do it.
I think my options are:
1) Upgrade the OS to 16.04 and then to 18.04 (all LTS) and then run the migration tools of Bonita;
2) Migrate all the Bonita sw/settings to a newly installed 18.04 Ubuntu server and then upgrade Bonita with the migration tools;
3) Install a new 18.04 Ubuntu server from scratch, install a new 'empty' Bonita software at the latest version and, at last, import data/settings from the old instance (if it's possible at all).
All three ways seem subject to many possible criticalities, and I'm not a real system manager (nor an expert of Bonita or JBoss).
What should I consider in order to take a decision?
I have a test environment available, in order to test the process before doing it in the production system.
Thank you all for your help,

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