apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/environment/Env.java/Env/transformToEnvMap
class Env:  static Map<Env, String> transformToEnvMap(Map<String, String> metaServerAddresses) {
    // add to domain
    Map<Env, String> map = new ConcurrentHashMap<>();
    for (Map.Entry<String, String> entry : metaServerAddresses.entrySet()) {
      // add new environment
      Env env = Env.addEnvironment(entry.getKey());
      // get meta server address value
      String value = entry.getValue();
      // put pair (Env, meta server address)
      map.put(env, value);
    }
    return map;
  }