most of the encumbrances for which IcedTea was providing replacements (less than 1% of encumbered code remains in the class library, and this code is not necessary to run OpenJDK). OpenJDK 6 was a stable branch, whereas OpenJDK 7 was unstable and not expected to ship a stable release until 2009. Sun has licensed the OpenJDK trademark for use in Fedora. In June 2008, it was announced that IcedTea 6 (as the packaged version of OpenJDK on Fedora 9) had passed the Technology Compatibility Kit tests and can claim to be a fully compatible Java 6 implementation. In September 2013, Azul Systems released Zulu, a free, open source build of OpenJDK for Windows Server and the Microsoft Azure Cloud. Later releases added support for Mac OS X, multiple versions of Linux and the Java Platform, Standard Edition version 8. Zulu is certified compliant with Java SE 8, 7 and 6 using the OpenJDK Community Technology Compatibility Kit. Amazon have released Amazon Corretto a no-cost, multiplatform, production-ready distribution of the Open Java Development Kit. It is released under GPL v2 with the Classpath Exception. Long term support versions of Java 8 and Java 11 are available. It was first publicly released on 31 January 2019. In 2017, the Eclipse Foundation released AdoptOpenJDK, now named Adoptium, who's main goal is "to promote and support free and open-source high-quality runtimes and associated technology for use across the Java ecosystem." See also Java (software platform) Javac HotSpot Apache Harmony OpenJDK GNU Classpath and GCJ IcedTea JamVM IKVM.NET List of Java virtual machines Comparison of Java virtual machines Adoptium References External links Free But Shackled - The Java Trap Escaping the Java Trap: A practical road map to the Free Software and Open Source alternatives Hybrids Combine GNU Classpath and OpenJDK Hour long 2007 video of a workshop with Sun, GGJ, and GNU Classpath developers Java Trademark Issues Java virtual machine Free virtualization software