Hi,
I’ve had a chance to start looking at this.
I’ve left a few comments on your PR but a bigger change is needed. Your plugin key (i.e. the name of the file) can’t simply be the name of a language. In fact, “rust” is specifically listed as a “don’t do” example for choosing a plugin key. 
Since you import Clippy lint reports, maybe rustclippy? Or communityrust? Or…
The rest of the bureaucratic requirements look good except for number 9, which I’ll look at when I do my testing.
Also, can you point me to a project to test with? Hopefully one that already has a Clippy report available?
Even before running an analysis, I see in the interface that you’ve added the Rust language and registered the file extension. Cool.
You’ve also provided a default profile but there are no rules, so the profile is empty. This is really weird.
I guess you’re importing the Clippy issues as external issues…? Is this something you plan to change in the future? Because as-is I have to wonder why you’re declaring the language and not just providing a pure utility to import Clippy issues (on unrecognized files). I guess you’ve declared the language so you can also import coverage data? If so… I think I’m going to have to hold out for a non-empty default profile. 
Ann