spring boot do not support META-INF/resources in jar jar

[hengyunabc]

I write a demo to support META-INF/resources in jar jar and jsp.

https://github.com/hengyunabc/spring-boot-fat-jar-jsp-sample

When start the demo with -Dtomcat.staticResourceCustomizer.enabled=false

java -Dtomcat.staticResourceCustomizer.enabled=false -jar jsp-start/target/jsp-start-0.0.1-SNAPSHOT.jar

http://localhost:8080/ 404

http://localhost:8080/hello-from-common ok

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The root reason is that LaunchedURLClassLoader urls do not contains the fat jar.

The parent of LaunchedURLClassLoader is AppClassLoader, which urls contains the fat jar

[wilkinsona]

Duplicate of #8324.

Also, please note that we don't support the use of JSPs in fat jars. You should use a war file instead.