JMeter: within JSR223 script get total number of samplers within a particular thread group

I have this JMeter test plan

How can get number of samplers within "Test 1 Thread Group" (3 in this particular example)?

Here is a full Java JSR223 sampler code to find out number of samplers in ThreadGroup with particular name:

import org.apache.jmeter.save.SaveService;
import org.apache.jmeter.services.FileServer;
import java.io.File;
import org.apache.jmeter.testelement.TestPlan;
import org.apache.jmeter.threads.AbstractThreadGroup;
import org.apache.jmeter.threads.ThreadGroup;
import org.apache.jorphan.collections.HashTree;
import org.apache.jorphan.collections.ListedHashTree;
import org.apache.jorphan.collections.SearchByClass;
import org.apache.jmeter.testelement.TestElement;
import org.apache.jmeter.samplers.AbstractSampler;
import org.apache.jmeter.control.GenericController;

log.info("----------------------------------------------------");

String basePath = FileServer.getFileServer().getBaseDir();
String jmxFile = basePath + File.separator + "test.jmx";
File file = new File(jmxFile);
HashTree tree = SaveService.loadTree(file);

static int getNumberOfSamplers(String threadGroupName) {
    for (Map.Entry entry : tree.entrySet()) {
        if (entry.getKey() instanceof TestPlan) {
            HashTree testplan = (HashTree) entry.getValue();

            for (Map.Entry element : testplan.entrySet()) {
                if (element.getKey() instanceof AbstractThreadGroup) {
                    AbstractThreadGroup myGroup = (AbstractThreadGroup) element.getKey();
                    if (myGroup.getName().equals(threadGroupName)) {
                        SearchByClass samplerSearch = new SearchByClass(AbstractSampler.class);
                        element.getValue().traverse(samplerSearch); // element.getValue() is ListedHashTree
                        return samplerSearch.getSearchResults().size();
                    }
                }
            }
        }
    }
    return 0;
}
log.info(getNumberOfSamplers("Test 1 Thread Group").toString());
log.info(getNumberOfSamplers("Test 2 Thread Group").toString());


log.info("----------------------------------------------------");