public S setParameter(String key, String value) {
        if (parameters == null) {
            parameters = new ConcurrentHashMap<String, String>();
        }
        if (value == null) {
            parameters.remove(key);
        } else {
            parameters.put(key, value);
        }
        return castThis();
    }
Gets app name.

@return the app name
core/api/src/main/java/com/alipay/sofa/rpc/config/AbstractInterfaceConfig.java