What is that minefield? How is avoided by repackagers? Do they take legal liability of Oracle lawsuits related to Java?
The other vendors have different (typically more explicitly open) licensing on their shipped artifacts. As ever, if it really matters, it's time to consult a legal professional in your jurisdiction to be sure instead of taking a random internet nerd's opinion on it. ;)
Oracle JDK: https://www.oracle.com/java/technologies/downloads/ (Oracle No-Fee Terms and Conditions)
The license you linked does not apply to current JDK versions at all.
GPL is a copyleft license, so if you would take linux kernel (same license), added some patches to it and you would distribute the resulting software, you would have to make sure your sources are available.
This would make Java as a runtime a very bad target for any company - they don’t want to share their application code - hence the classpath exception, giving you basically a boundary over which the copyleft doesn’t propagate over.
But the JVM itself still benefits from any updates made by any company.
Oooh that makes sense, thanks for clarifying this!
"But almost all of this would have been available elsewhere under a standard open source licence!" is worth exactly nothing if one day you discover that you failed to stay clear of all their friendly little traps.
The other vendor's shipped artifacts are in turn the work product of those vendors, based on the OpenJDK core. They are not distributing Oracle software, they are distributing artifacts built from the OpenJDK project's software, and their licensing decisions are independent of constraint from Oracle.
The Oracle build of the JDK has not always been isomorphic to those produced based on the OpenJDK code, and has in the past had different license terms that can in no way be characterized as a standard open source license. See, for example, graalvm use in production environments with OracleJDK. Being transparent, this may have changed in the past few years; ever since I left Oracle I've tried to think about their existence as little as possible.
My overall point is that it is wise, based on Oracle's past history, to read and carefully evaluate the license terms for Oracle's software before you use any of it in a commercial context. The strictly-GPLv2-with-classpath-exception-sourced vendor distributions of OpenJDK, not so much as the license is in fact standard and widely used/understood already in both commercial and non-commercial situations.
That's not true. Oracle owns the OpenJDK project much like Google owns Chromium. To contribute to OpenJDK you need to sign a Contributor Agreement granting Oracle shared ownership over your contribution (i.e. you maintain copyright, but Oracle also has copyright); this is standard practice for such open-source projects (like Chromium). On the other hand, while Linux is developed by various for-profit companies, the code is owned by the Linux Foundation. As of now, there is no separate legal entity for OpenJDK. I'm not sure it makes a difference in practice, but if you wanted to be technically correct then that's the situation.
> The Oracle build of the JDK has not always been isomorphic to those produced based on the OpenJDK code,
No. We offer two builds of the OpenJDK JDK, under two different licenses. The open-source one is here: https://jdk.java.net It is an official Oracle build.
The other official Oracle build (called by various names, including Oracle JDK) has a different license, but only diverges from OpenJDK some time after a feature release due to different bugfix backports.
> The strictly-GPLv2-with-classpath-exception-sourced vendor distributions of OpenJDK
Just pointing out that Oracle also distributes the JDK under that very same license (https://jdk.java.net), but we also offer our software through other vendors. It's up to you which website you choose to download our software from.
> This page provides production-ready open-source builds of the Java Development Kit, version 21, an implementation of the Java SE 21 Platform under the GNU General Public License, version 2, with the Classpath Exception.
This is incorrect. Linux does not require copyright assignment.
The documentation [0] says: "Copyright assignments are not required (or requested) for code contributed to the kernel. All code merged into the mainline kernel retains its original ownership; as a result, the kernel now has thousands of owners."
[0] https://www.kernel.org/doc/html/latest/process/1.Intro.html#...
The only remaining differences between OracleJDK and OpenJDK are logo, and trivial things - Oracle has opened up everything else.
Like making it even more free? You are literally free to use the “paid” OracleJDK on its latest LTS release up until the next LTS comes around+1 year.
So that’s why you shouldn’t download from Oracle.
Builds for the former are open-source but only updated for 6 months after each release, while the latter is under a commercial license with 3+ years commercial long-term support for some versions.
Projects like Eclipse Temurin (Adoptium) bring the LTS to OpenJDK. The underlying code is entirely open-source, so there is no licensing trouble.
Hence, if you want to download OpenJDK, it's important to do it from Adoptium, as you won't get updates on java.net after a while.
One can optionally buy support for it, that’s the whole deal. Not that hard, but apparently this is a minefield for some..