code: public void run() {
          if (isCompleted()) {
              log.info("Not executing tests as application state is completed!");
              return;
          }
  
          log.info(String.format("Running Citrus %s", Citrus.getVersion()));
          setDefaultProperties(configuration);
  
          if (ClassUtils.isPresent("org.testng.annotations.Test", getClass().getClassLoader())) {
              new TestNGEngine(configuration).run();
          } else if (ClassUtils.isPresent("org.junit.Test", getClass().getClassLoader())) {
              new JUnit4TestEngine(configuration).run();
          }
      }
docs: Run application with prepared Citrus instance.