@Override
    @SuppressWarnings("unchecked")
    public <T> T get(ConfigType configType, ConfigItem configItem) {
        validate(configType, configItem);
        if (userConfigs.containsKey(configType)) {
            return (T) userConfigs.get(configType).get(configItem);
        }
        return null;
    }
use a hash map to store the user configs with different config types and config items.
src/main/java/com/alipay/remoting/config/configs/DefaultConfigContainer.java