I have a very simple library with classes in one package. As far as I know, it only depends on things in java.base. I added a module-info.java to the top level directory that exports this package.
e.g.
module org.foo.bar {
exports org.foo.bar.pkgname;
}
I then just built a simple jar file with my classes and the module-info class.
Is that it, or is there more that I need to do?
That's it, as long as your jar is organized as follows:
module-info.class
org
foo
bar
pkgname
X.class
Y.class
A jar with a module-info.class at top level is a module. You can check your module with:
jar --describe-module --file bar.jar