I'm trying to install org.apache.commons.cli so it will work with OpenJDK 8. I want to install it from Eclipse (Neon) but I can't seem to figure out the url I need to add in the Install new software. I was looking in the official website and I tried both the url that are shown there but they both didn't work. How should I install it?
"Install new software" is for adding features to Eclipse itself, not for downloading third-party libraries for your application. For that, you either use a build script (Maven, Gradle, Ivy, ...) for your project, or you download the library code and add it as "External Archive" to the Build Path of your project.