apollo-core/src/main/java/com/ctrip/framework/apollo/core/enums/EnvUtils.java/EnvUtils/transformEnv
class EnvUtils:  public static Env transformEnv(String envName) {
    if (StringUtils.isBlank(envName)) {
      return Env.UNKNOWN;
    }

    String cleanedEnvName = envName.trim().toUpperCase();

    // fix up in case there is a typo
    // like prod/pro
    if (cleanedEnvName.equals("PROD")) {
      return Env.PRO;
    }

    if (cleanedEnvName.equals("FWS")) {
      // special case that FAT & FWS
      // should return the same
      return Env.FAT;
    }

    try {
      return Env.valueOf(cleanedEnvName);
    } catch (IllegalArgumentException e) {
      // the name could not be found
      // or there is a typo we dont handle
      return Env.UNKNOWN;
    }
  }