apollo-core/src/main/java/com/ctrip/framework/apollo/core/MetaDomainConsts.java/MetaDomainConsts/initMetaServerProviders
class MetaDomainConsts:  private static List<MetaServerProvider> initMetaServerProviders() {
    Iterator<MetaServerProvider> metaServerProviderIterator = ServiceBootstrap
        .loadAll(MetaServerProvider.class);

    List<MetaServerProvider> metaServerProviders = Lists.newArrayList(metaServerProviderIterator);

    Collections.sort(metaServerProviders, new Comparator<MetaServerProvider>() {
      @Override
      public int compare(MetaServerProvider o1, MetaServerProvider o2) {
        // the smaller order has higher priority
        return Integer.compare(o1.getOrder(), o2.getOrder());
      }
    });

    return metaServerProviders;
  }