That doesn't mean it's plagiarized. Any academic paper is going to have supporting data and points from outside sources such as academic journals, websites, books and so on. That actually helps solidify its authenticity. But the design of the paper is the writers, as is the context and points made within. Supporting data is brought from external sources.
Plagiarized means the design or elements of it have been taken from other platforms, and only marginally altered (if at all). It doesn't mean the platform incorporates or does not incorporate foreign technology.
In the case of the JAS39, it incorporates foreign technology, but it doesn't copy them or alter their designs. Rather, it uses them on a design developed by Sweden as a successor the Viggen, from which the JAS39 gets some of its requirements and design elements, like the canards which provide greater lift for take-offs from short or highway runways, as Sweden uses and which provides excellent maneuverability.
The Gripen didn't take canards from the Typhoon just because the Typhoon had them. That would be plagiarized. Developing an in-house platform with elements that meet your requirements, developing from existing platforms within your military and acquiring foreign technology which you don't alter, that is not plagiarism. That's the normal development of every aircraft in the world. All of them.
Looking at the Viggen above, you can clearly see design elements from it have been used in the Gripen too. Both come from the same company, SAAB.
1. I'm a lady.
2. I didn't mention Tejas. I was answering on why the Gripen isn't a "plagiarized" platform, as was asked about it in the OP.
