There is also a dependency you need to install to get the plugin api working, but i forget what that is atm I have had it working in the past but it isn't easy to find the right one.
In order to RUN plugins you will need the Java Runtime Environment Standard Edition (JRE SE) - but I am pretty sure that RW comes with this bundled into it.
However, here is the JRE SE for Java 8 fi you want to install it manually -https://www.java.com/en/download/manual.jsp
If you want to MAKE plugins, you will need the Java Development Kit (JDK SE) - https://www.oracle.com/uk/java…e8-archive-downloads.html
There is a JDK EE and JDK ME (enterprise and micro) - you don't need these.