apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/environment/Env.java/Env/addEnvironment
class Env:  public static Env addEnvironment(String name) {
    if (StringUtils.isBlank(name)) {
      throw new RuntimeException("Cannot add a blank environment: " + "[" + name + "]");
    }

    name = getWellFormName(name);
    if (STRING_ENV_MAP.containsKey(name)) {
      // has been existed
      logger.debug("{} already exists.", name);
    } else {
      // not existed
      STRING_ENV_MAP.put(name, new Env(name));
    }
    return STRING_ENV_MAP.get(name);
  }