Ignore the empty nacos configuration and get it based on dataId[common.yaml] & group[DEFAULT_GROUP]

To ignore the empty Nacos configuration and get it based on dataId[common.yaml] & group[DEFAULT_GROUP], you can use the following code in Java:

import com.alibaba.nacos.api.NacosFactory;
import com.alibaba.nacos.api.config.ConfigService;
import com.alibaba.nacos.api.config.listener.Listener;
import com.alibaba.nacos.api.exception.NacosException;

import java.util.Properties;
import java.util.concurrent.Executor;

public class NacosConfigExample {

    public static void main(String[] args) throws NacosException {
        String serverAddr = "localhost:8848";
        String dataId = "common.yaml";
        String group = "DEFAULT_GROUP";

        Properties properties = new Properties();
        properties.put("serverAddr", serverAddr);

        ConfigService configService = NacosFactory.createConfigService(properties);

        String content = configService.getConfig(dataId, group, 5000);
        if (content == null || content.isEmpty()) {
            System.out.println("Empty configuration!");
        } else {
            System.out.println(content);
        }
    }
}

This code uses the Nacos API to create a `ConfigService` instance and retrieve the configuration based on the specified `dataId` and `group`. If the configuration is empty, it prints a message to the console.