Suppose I have Java jar-files which I provide to my customers under a commercial closed-source license. But my jar-files depend on a few jar-files released under the GPLv2 (without any special GNU Classpath exception or anything like that).
If I give my customers both my jar-files and the GPLv2 jar-files as a complete product, then I am obviously violating the GPLv2: I am (dynamically) linking the GPLv2 jar-files, which by the GPL requires me to provides access to also our my source files. [Well, fairly obviously. I know dynamic linking is a grey area in GPL land, but I want to be on the safe side and assume this scenario violates the GPLv2.]
However, what if I deliver the product incompletely, and ask my customers to download the GPLv2 jar-files themselves separately?
What would be the legal status in that scenario?
What I do then is deliver an incomplete product, which depends on an API (as opposed to specific GPLv2 jar-files), which the customer in theory could implement by creating their own GPL'd or closed source or public domain jar-files implementing that API. So I would be delivering an incomplete closed source product which doesn't depend on any GPL'd artifact. That seems legal?
And would the customer then be violating the GPLv2 by running our incomplete closed source product with the GPLv2 jar-files?
Note: I'm not asking here whether this scenario would be morally acceptable. :-)
Versions of this same question have been asked before: Dynamic linking, bundling, and GPL and Using GPL resource (with separate installation) with "commercial" product and Automated GPL download and installation in BSD project. But I don't see an answer there that addresses the bundle-vs-separate legal status. I would appreciate authoritative references if available.