Fix regression in `JarUrlConnection` where a NullPointerException could
be thrown internally causing performance issues.
When the SecurityManager is present, the following stack trace is
thrown:
java.lang.NullPointerException: Cannot invoke "java.net.URLConnection.getPermission()" because "this.jarFileConnection" is null
at org.springframework.boot.loader.net.protocol.jar.JarUrlConnection.getPermission(JarUrlConnection.java:175)
at java.base/jdk.internal.loader.URLClassPath.check(URLClassPath.java:553)
at java.base/jdk.internal.loader.URLClassPath$Loader.findResource(URLClassPath.java:612)
at java.base/jdk.internal.loader.URLClassPath.findResource(URLClassPath.java:296)
at java.base/java.net.URLClassLoader$2.run(URLClassLoader.java:629)
at java.base/java.net.URLClassLoader$2.run(URLClassLoader.java:627)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
at java.base/java.net.URLClassLoader.findResource(URLClassLoader.java:626)
at org.springframework.boot.loader.net.protocol.jar.JarUrlClassLoader.findResource(JarUrlClassLoader.java:70)
at java.base/java.lang.ClassLoader.getResource(ClassLoader.java:1403)
at java.base/java.net.URLClassLoader.getResourceAsStream(URLClassLoader.java:290)
at java.base/java.lang.Class.getResourceAsStream(Class.java:2850)
See gh-39856
5b4bd61720