this is simple for kotlin use spring boot 1.4.2 with
fastjson
druid
beetl
beetlsql

NOTE:this test in war package and use java -jar xxx.war to run embed tomcat.

use ide to start spring-boot with maven commend mvn spring-boot:run then classpath root is target/classes
run packaged war with java commend java -jar xxx.war then classpath root is /xxx/xxx/xxx.war!/, so this project code BeetlAutoConfiguration.getBeetlGroupUtilConfiguration check WEB-INF/classes/ is exist

beetl view template is in resources/templates, but if your maven pom config jar package, the view template is in resource/static or you can modify application.properties config
spring.resources.static-locations=classpath:/META-INF/resources/,classpath:/resources/,classpath:/static/,classpath:/public/ # Locations of static resources.

reference:
http://git.oschina.net/xiandafu/springboot_beetl_beetlsql