05.3) Application entryPoint Classs
@SpringBootApplication annotation is a composed annotation
@EnableAutoConfiguration enables SpringBoot’s auto-configuration support
@ComponentScan enables component scanning of current package
Also recursively scans sub-packages
@Configuration indicates that this class is a Spring configuration class.
- NONE : the application should not run as a web application and should not start an embedded web server
- REACTIVE : the application should run as a reactive web application and should start an embedded reactive web server
- SERVLET : the application should run as a servlet-based web application and should start an embedded servlet web server
- default : 라이브러리를 확인하고 설정