public String toXmlString() {
    switch (name) {
      case "INVALIDATE":
        return "invalidate";
      case "DESTROY":
        return "destroy";
      case "LOCAL_DESTROY":
        return "local-destroy";
      case "LOCAL_INVALIDATE":
        return "local-invalidate";
      default:
        return null;
    }
  }
converts to strings used in cache.xml

@return strings used in cache.xml
geode-core/src/main/java/org/apache/geode/cache/ExpirationAction.java