https://blog.faceutil.com/2017/04/04/1-8-%eb%a7%88%ec%9d%b8%ed%81%ac%eb%9e%98%ed%94%84%ed%8a%b8-server-properties-%ed%8c%8c%ec%9d%bc-%ec%84%a4%ec%a0%95%eb%b2%95-%e3%8e%94/