I can successfully start spring-boot with mvn spring-boot, the documentation mentions to gracefully exit the application hit ctrl-c.
This solution worked for me with Spring Boot v1.x und works now, with v2.x:
hangingJavaProcessToStop=`jps | grep Application | awk '{print $1}'`
echo "hangingJavaProcessToStop: $hangingJavaProcessToStop"
kill -9 $hangingJavaProcessToStop
This way you can kill specifically Spring Boot's Application Java process instead of killing all Java processes at once. I assume if your Spring Boot "Application" (main method containing class) is called differently, you must use its name instead of Application.
I am running the snippet above, on my Windows machine using WSL/Debian. I am not using PowerShell or Windows'command line.