Confused about CLASSPATH I think

I'm trying to build the open source application found at: https://github.com/linklayer/cantact-app

I've installed netbeans and gotten to the point that I can create a new project. I got help doing this via Netbeans installed via APT opens but then closes, "java.lang.NoClassDefFoundError"

Now I'm still at a loss for how to set CLASSPATH in order to get the "ant build" command to work for cantact-app. When I look at ~/.netbeans/8.2/var/log/messages.log, I don't see an actual "CLASSPATH". Instead, I see a "Boot & Ext. Classpath", a "Application Classpath", and a "Startup Classpath". Well I took the value of "Application Classpath" and did an "export CLASSPATH=..." for that long path. Now, "ant build" still gets a "BUILD FAILED" with message "Cannot find NetBeans build harness. Check that nbplatform.default.netbeans.dest.dir and nbplatform.default.harness.dir are defined..."