code: package io.ray.test;
  
  import com.google.common.collect.ImmutableList;
  import java.util.List;
  import org.testng.IClassListener;
  import org.testng.ITestClass;
  
  public class SystemPropertyListener implements IClassListener {
    private final List<String> whitelist = ImmutableList.of("ray.run-mode");
  
    @Override
    public void onAfterClass(ITestClass testClass) {
      for (String key : System.getProperties().stringPropertyNames()) {
        if (key.startsWith("ray.")) {
          if (!whitelist.stream().anyMatch(key::equals)) {
            System.clearProperty(key);
          }
        }
      }
    }
  }
  