A lint check to ensure each file contains at most 1 kotlinx.android.synthetic import
It is fairly easy to import synthetic extensions for the wrong layout file, thus causing NullPointerExceptions.
This is a common source of bugs, and is arguably the biggest motivation to use ViewBinding over Synthetics.
However, Synthetics are still widely prefered over ViewBinding, for many reasons. With this lint check, the biggest advantage of ViewBinding over Synthetics becomes moot.
You should only have 1 synthetic import in each file. Having more than 1 synthetic import in a file is usually an mistake. If not a mistake, it is in any case confusing and therefore discouraged.
What if you really, really, really need to import multiple synthetic imports in a single file?
First of all, consider reworking the code - prefer to encapsulate logic related to each XML layout in its own Custom or Compound View.
If you still need to import multiple synthetic imports in a single file, you can suppress the lint check by adding this line as the very first line in your file:
Use via Jitpack: https://jitpack.io/#Innovattic/multiple-synthetic-import-lint