public static PostProcessor getPostProcessor(Properties properties) {
    String postProcessorConfig = properties.getProperty(SECURITY_POST_PROCESSOR);
    if (StringUtils.isBlank(postProcessorConfig)) {
      return null;
    }
    PostProcessor postProcessor =
        getObjectOfTypeFromClassName(postProcessorConfig, PostProcessor.class);
    postProcessor.init(properties);
    return postProcessor;
  }
this method would never return null, it either throws an exception or returns an object
geode-core/src/main/java/org/apache/geode/internal/security/CallbackInstantiator.java