How do I pass a property through the API and how can I access a tagDatabase tag value

I use the following sequence to start a migration, which works fine:

  1. Liquibase liquibase = new Liquibase(changelog_path, liquires, db);
  2. liquibase.update(null);

As far as I can see update can take a String with contexts but how can I pass parameters to Liquibase?

Can I just set a system property with

  1. System.setProperty(key, value) ?

I’d also like to evaluate a database tag in preconditions. Is that possible?

Thanks  Hans