ThreadPoolExhaustedListener 在最新版本中未发现用户配置的入口，这个功能的设计初衷我理解，是发生线程池耗尽通知给应用，目前没看到应用如何添加监听的地方。
*/
    String EXTRA_KEYS_KEY = "extra-keys";
    String GENERIC_SERIALIZATION_NATIVE_JAVA = "nativejava";
    String GENERIC_SERIALIZATION_GSON = "gson";
    String GENERIC_SERIALIZATION_DEFAULT = "true";
    String GENERIC_SERIALIZATION_BEAN = "bean";
    String GENERIC_RAW_RETURN = "raw.return";
    String GENERIC_SERIALIZATION_PROTOBUF = "protobuf-json";
    String GENERIC_WITH_CLZ_KEY = "generic.include.class";
    /**
     * Whether to cache locally, default is true
     */
    String REGISTRY_LOCAL_FILE_CACHE_ENABLED = "file.cache";
    /**
     * The limit of callback service instances for one interface on every client
     */
    String CALLBACK_INSTANCES_LIMIT_KEY = "callbacks";
    /**
     * The default limit number for callback service instances
     *
     * @see #CALLBACK_INSTANCES_LIMIT_KEY
     */
    int DEFAULT_CALLBACK_INSTANCES = 1;
    String LOADBALANCE_KEY = "loadbalance";
    String DEFAULT_LOADBALANCE = "random";
    String RETRIES_KEY = "retries";
    String FORKS_KEY = "forks";
    int DEFAULT_RETRIES = 2;
    int DEFAULT_FAILBACK_TIMES = 3;
    String INTERFACES = "interfaces";