apollo-core/src/main/java/com/ctrip/framework/apollo/core/enums/ConfigFileFormat.java/ConfigFileFormat/fromString
class ConfigFileFormat:  public static ConfigFileFormat fromString(String value) {
    if (StringUtils.isEmpty(value)) {
      throw new IllegalArgumentException("value can not be empty");
    }

    final String cleansedName = getWellFormedName(value);

    return Stream.of(ConfigFileFormat.values())
        .filter(item -> cleansedName.equalsIgnoreCase(item.getValue()))
        .findFirst()
        .orElseThrow(() -> new IllegalArgumentException(value + " can not map enum"));
  }