Force source archives to be included with legacy JAR modules

[hwellmann]

Currently, all of the legacy JAR modules in Herd lack a source attachment, so it's impossible to debug into a JAR module (Ceylon Eclipse doesn't even let you specify a source archive manually).

Herd should refuse any uploads without a matching source attachment.

[FroMage]

We don't enforce the presence of source files even for Ceylon archives, so we won't for Java either. But we should support having source files for Java archives yes.

(Ceylon Eclipse doesn't even let you specify a source archive manually).

That's an issue you should report on the IDE.

[hwellmann]

Here's the IDE issue: https://github.com/ceylon/ceylon-ide-eclipse/issues/782

What's the rationale for not requiring source archives? It's just a nuisance when they're missing. This is a chance for Herd to be better than Maven Central :-)

[FroMage]

I guess the rationale is that if people depend on something that is closed-source but redistributable, we shouldn't make it impossible to use it. It's certainly a debate we can have.

[davidfestal]

By the way, if you use Java modules from Maven (through the aether repository), you'll have the sources automatically downloaded and attached to the module. It seems to me that as soon as sources are downloaded automatically along with the binary archive, we don't need to allow changing the source attachment manually. But for those that don't have sources in Maven or Herd, it would surely be useful