So, it is not a joint fighter.
It is Joint fighter by all means, if you think rationally without any bias. "Joint fighter" does not mean an equal technical participation. It could be at any level of technical, or at level of project ownership, or at level of financials.
Pakistan initiated this project with a chinese aviation firm (PAC and CATIC). Pakistan paid for the R&D, Pakistan is the co-owner of the project. That's all more than enough to call it a joint-fighter, even if you don't count the teams of engineers, pilots, local parts or whatever. We don't shy to accept that Pakistan imports engine and several parts of it but that doesn't mean we don't own it.
India also import several of Tejas components, including most critical component of any aircraft its engine, and several israeli / french / british components. Does that mean Tejas is not indian? India financed it, india owns it, so that's enough. Keep same principle on judging all aircrafts.
I see some insane arguments sometimes considering JF-17 project same as liscenced production of SU-30s. India never owns SU-30, that aircraft is ownership of Russia, SU-30 was already designed and developed before india opts in for liscence production, india never paid for its initial concept, never founded the su-30 project, never paid for its R&D. You are just a liscence producer. Incase of JF-17 try to grasp the concept of ownership, Pakistan owns and is part when the aircraft was just a concept, there is jointness at every step. Hope you understand now and got the idea.