Add an "ultimate threadgroup " in jmeter via java code

It would be something like:

UltimateThreadGroup threadGroup = new UltimateThreadGroup();
threadGroup.setName("Ultimate Thread Group");
CollectionProperty ultimatethreadgroupdata = new CollectionProperty("ultimatethreadgroupdata", new ArrayList<>());
CollectionProperty schedule1 = new CollectionProperty("schedule1", new ArrayList<>());
Arrays.asList("100", "50", "20", "120", "40").forEach(schedule1::addItem);
ultimatethreadgroupdata.addProperty(schedule1);
threadGroup.setData(ultimatethreadgroupdata);

Just remember to:

1. Add kg.apc.jmeter-plugins-casutg library along with dependencies to your project classpath, otherwise it won't compile
2. Install Custom Thread Groups bundle using JMeter Plugins manager, otherwise you will not be able to run the script.