OpenJDK 11 is a Long-Term Support (LTS) release of the Java platform.

For a list of major changes from OpenJDK 8 (java-1.8.0-openjdk), see

the upstream release page for OpenJDK 11 and the preceding interim

releases:

* 9: https://openjdk.org/projects/jdk9/

* 10: https://openjdk.java.net/projects/jdk/10/

* 11: https://openjdk.java.net/projects/jdk/11/

# Rebuilding the OpenJDK package

The OpenJDK packages are now created from a single build which is then

packaged for different major versions of Red Hat Enterprise Linux

(RHEL). This allows the OpenJDK team to focus their efforts on the

development and testing of this single build, rather than having

multiple builds which only differ by the platform they were built on.

This does make rebuilding the package slightly more complicated than a

normal package. Modifications should be made to the

`java-11-openjdk-portable.specfile` file, which can be found with this

README file in the source RPM or installed in the documentation tree

by the `java-11-openjdk-headless` RPM.

Once the modified `java-11-openjdk-portable` RPMs are built, they

should be installed and will produce a number of tarballs in the

`/usr/lib/jvm` directory. The `java-11-openjdk` RPMs can then be

built, which will use these tarballs to create the usual RPMs found in

RHEL. The `java-11-openjdk-portable` RPMs can be uninstalled once the

desired final RPMs are produced.

Note that the `java-11-openjdk.spec` file has a hard requirement on

the exact version of java-11-openjdk-portable to use, so this will

need to be modified if the version or rpmrelease values are changed in

`java-11-openjdk-portable.specfile`.

To reduce the number of RPMs involved, the `fastdebug` and `slowdebug`

builds may be disabled using `--without fastdebug` and `--without

slowdebug`.