apollo-client-config-data/src/main/java/com/ctrip/framework/apollo/config/data/system/ApolloClientSystemPropertyInitializer.java/ApolloClientSystemPropertyInitializer/fillSystemPropertyFromBinder
class ApolloClientSystemPropertyInitializer:  private void fillSystemPropertyFromBinder(String propertyName, String bindName, Binder binder,
      BindHandler bindHandler) {
    if (System.getProperty(propertyName) != null) {
      return;
    }
    String propertyValue = binder.bind(bindName, Bindable.of(String.class), bindHandler)
        .orElse(null);
    if (!StringUtils.hasText(propertyValue)) {
      return;
    }
    log.debug(Slf4jLogMessageFormatter
        .format("apollo client set system property key=[{}] value=[{}]", propertyName,
            propertyValue));
    System.setProperty(propertyName, propertyValue);
  }