code: private StagedExamReactorFactory getStagingFactory(Class<?> testClass) {
          ExamReactorStrategy strategy = testClass.getAnnotation(ExamReactorStrategy.class);
          String strategyName = cm.getProperty(EXAM_REACTOR_STRATEGY_KEY);
          StagedExamReactorFactory fact;
          try {
              if (strategy != null) {
                  fact = strategy.value()[0].newInstance();
                  return fact;
              }
          }
          catch (IllegalAccessException | InstantiationException exc) {
              throw new TestContainerException(exc);
          }
  
          if (strategyName == null) {
              if (systemType.equals(EXAM_SYSTEM_CDI) || systemType.equals(EXAM_SYSTEM_JAVAEE)) {
                  strategyName = EXAM_REACTOR_STRATEGY_PER_SUITE;
              }
              else {
                  // OSGi default from Pax Exam 2.x
                  strategyName = EXAM_REACTOR_STRATEGY_PER_METHOD;
              }
          }
          fact = reactorStrategies.get(strategyName);
          if (fact == null) {
              throw new IllegalArgumentException("unknown reactor strategy " + strategyName);
          }
          return fact;
      }
docs: Creates a staging factory indicated by the {@link ExamReactorStrategy} annotation of the test
  class.
  
  @param testClass
  @return staging factory