Licensing for OpenJDK is non trivial. Look at the large table and various bullet points Oracle had to make to tell you the license. https://www.oracle.com/java/technologies/javase/jdk-faqs.htm... (open the first dropdown on their FAQ page to open up their "licensing matrix")

This is a mess, and is the license going to change again while I'm locked in the java ecosystem?

Edit: It looks like the openjdk is consistently under the gplv2, I don't know why it has so many different entries in their table. I think I probably got opendjk and oracle jdk mixed up. I think the person I was replying to who said openjdk needs to be updated every half year got confused as well. It's so hard to even talk about all the different jdks without getting them mixed up or confused. Again, no other java competitors have this problem.