According to the packages list in Ubuntu Wily Xenial Bionic there is a package named openjfx. This should be a candidate for what you're looking for:
JavaFX/OpenJFX 8 - Rich client application platform for Java
You can install it via:
sudo apt-get install openjfx
It provides the following JAR files to the OpenJDK installation on Ubuntu systems:
/usr/lib/jvm/java-8-openjdk-amd64/jre/lib/ext/jfxrt.jar
/usr/lib/jvm/java-8-openjdk-amd64/jre/lib/jfxswt.jar
/usr/lib/jvm/java-8-openjdk-amd64/lib/ant-javafx.jar
/usr/lib/jvm/java-8-openjdk-amd64/lib/javafx-mx.jar
If you want to have sources available, for example for debugging, you can additionally install:
sudo apt-get install openjfx-source