I have a very old Java programmer certification "back in the day when it was Sun Microsystems" which is SCJP 5 "Java 1.5" and since it has been a while and it feels like a new language all together, I want to ask what would be the best approach to update it to the most recent version possible?
does the book cover topics of upgrading the old certifications? as far as I remember previous editions of the book used to have a section for specifically the upgrade exam "or upgrade path".
For Java 8, there is the 1Z0-813 upgrade exam (expiring 2/29/2020) which I think supports SCJP5 certifications holders. That said, you need to make sure Oracle's CertView page has a record of you passing the SCJP5 cert, since this was administered back in the Sun days.
In theory, you could take the 1Z0-813 exam to get a Java 8 cert and then the 1Z0-817 exam to get the Java 11 cert... but I really wouldn't recommend it. First, you're basing a lot on an exam that's about to expire and whose records may be lost over time. More importantly, though, so much has changed it would be better for you to spend your time studying for the 1Z0-815 and 1Z0-816 exams. You'll learn a lot more.