How to have multiple JDKs parallel?

[Peter Nabbefeld <peter.nabbefeld@xxxxxx>]

Hello,

up to JDK 9 I didn't have problems upgrading, but since JDK 10 it always 
wants to replace JDK 9, and I guess it will become worse with JDK 11 etc.

I've set "IgnorePkg = jdk9-openjdk jre9-openjdk jre9-openjdk-headless 
openjdk9-doc openjdk9-src" in pacman.conf, so now I'm getting warnings 
all the time, but I'm not sure what will happen with future updates.

As a Java developer, I need to be able to have multiple JDKs for 
compatibility checkings.

Kind regards

Peter