There are a variety of JDK vendors. We test with the Azul JDK 11. Our only known requirement beyond JDK11 is that tomcat's https should recognize contemporary root certificates.

You have the following options to install JDK 11:

1. If you wish to install Azul JDK 11, please visit https://www.azul.com/downloads/zulu-community/ and follow the instructions there to download a compressed tarball archive and install your JDK.  Please ensure that it is at least version 11 or later.

2. If your Linux distribution provides another way to install a JDK, such as through a package manager like yum or apt-get, please consult those steps as they may offer better integration with your base operation system.  The following code is an example of installing JDK using yum, and then extracting its version information:

   $ sudo yum install openjdk $ java -version

No matter which option you choose to install JDK, be sure that your system environment variables are set to point "JAVA_HOME" and "JDK_HOME" to the correct locations.  If you are using bash shell, you can add a file in /etc/profile.d/ to include the following settings (this is just an example; please use your system's own settings):

export JAVA_HOME=/opt/where_your_jdk_lives
export JDK_HOME=$JAVA_HOME
export PATH=$JAVA_HOME/bin:$PATH
export MANPATH=$JAVA_HOME/man:$MANPATH