docker stop always takes 10 seconds even though the app shuts down instantly when killed manually

A Spring Boot service has ENTRYPOINT java -jar app.jar (shell form). docker stop always hits the full grace period. Diagnose and fix. Expected reasoning: shell form makes /bin/sh PID 1; SIGTERM is sent to the shell, not forwarded to the java child process, so java never receives the signal and the timeout always expires before SIGKILL. Fix: switch to exec form, ENTRYPOINT ["java","-jar","app.jar"], so java itself is PID 1 and Spring Boot's shutdown hooks run on SIGTERM.