per https://ask.clojure.org/index.php/12732/clojure-tools-namespace-throws-casting-error-calling-jarfile

symptom

If I call find-ns-decls-in-jarfile jarfile (example below) with any jar I get the exception:

Error printing return value (ClassCastException) at clojure.tools.namespace.find/read-ns-decl-from-jarfile-entry (find.clj:158).
class java.util.jar.JarFile cannot be cast to class java.io.File (java.util.jar.JarFile and java.io.File are in module java.base of loader 'bootstrap')