add swagger-API and example controller

src/main/resources/application.properties

@@ -9,9 +9,15 @@ spring.datasource.username=root
 spring.datasource.password=geheim
 spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
 
+<<<<<<< Updated upstream
 
 keycloak.principal-attribute=preferred_username
 keycloak.auth-server-url=https://keycloak.cs.hhu.de/auth
 keycloak.realm=MOPS
 keycloak.resource=demo
 keycloak.public-client=true
+=======
+spring.security.user.name=root
+spring.security.user.password=1234
+spring.security.user.roles=ADMIN
+>>>>>>> Stashed changes