According to documentation of JarResourceLoader it accepts paths that conform to rules given by java.net.JarUrlConnection. This is however not true as the JarUrlConnection says that the URL has form
The "!/" is mandatory part of the URL. JarResourceLoader however expects the path whitout this suffix and automatically appends it. When conforming URL is given JarResourceLoader makes it invalid
is scrambled to
which is invalid and no templates are found.
I try to package templates along with tools and other code. I put them into /META-INF/templates/ and try to setup the loader so I do not have to prefix template names with "/META-INF/templates/".
Ideally the JarResourceLoader should not append "!/" suffix at all. For compatibility reasons it should do so only if the path does not contain it already.