ClasspathUtil getClasspath() fails with cast exception

[howff]

The call to getClassLoader() fails with

class jdk.internal.loader.ClassLoaders$AppClassLoader cannot be cast to class java.net.URLClassLoader
(jdk.internal.loader.ClassLoaders$AppClassLoader and java.net.URLClassLoader are in module java.base of loader 'bootstrap')

Googling around suggests this hasn't worked since Java 9 and I'm on Java 11.

[howff]

Some more information
https://community.oracle.com/tech/developers/discussion/4011800/base-classloader-no-longer-from-urlclassloader