Spring Boot のアンダースコアつき環境変数

~/Documents/java/demo
❯ env 'logging.level.com.example.foo_bar.Baz=debug' java -jar target/demo-0.0.1-SNAPSHOT.jar 

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v2.6.3)

2022-02-19 22:22:18.914  INFO 39801 --- [           main] com.example.foo_bar.DemoApplication      : Starting DemoApplication v0.0.1-SNAPSHOT using Java 17.0.1 ...
2022-02-19 22:22:18.917  INFO 39801 --- [           main] com.example.foo_bar.DemoApplication      : No active profile set, falling back to default profiles: default
2022-02-19 22:22:19.660 DEBUG 39801 --- [           main] com.example.foo_bar.Baz                  : Hello World
2022-02-19 22:22:19.791  INFO 39801 --- [           main] com.example.foo_bar.DemoApplication      : Started DemoApplication in 1.472 seconds (JVM running for 2.103)

~/Documents/java/demo
❯ env 'logging.level.com.example.foo_bar.Baz=info' java -jar target/demo-0.0.1-SNAPSHOT.jar

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v2.6.3)

2022-02-19 22:22:37.268  INFO 40076 --- [           main] com.example.foo_bar.DemoApplication      : Starting DemoApplication v0.0.1-SNAPSHOT using Java 17.0.1 ...
2022-02-19 22:22:37.272  INFO 40076 --- [           main] com.example.foo_bar.DemoApplication      : No active profile set, falling back to default profiles: default
2022-02-19 22:22:38.184  INFO 40076 --- [           main] com.example.foo_bar.DemoApplication      : Started DemoApplication in 1.508 seconds (JVM running for 2.144)