SafeArgs generated classes (Directions/Args) are not recognized by lint in AS 3.5

Question

I'm migrating several apps to use the Navigation Component, and I ran into a problem - the Directions/Args classes generated by the android-safe-args-gradle-plugin are not being recognized in Android Studio.

Code demonstrating this problem is located at github.com/wooldridgetm/android-navigation.git, but crux of the matter is, in the code below, HomeFragmentDirections isn't recognized. This is taken from the class HomeFragment, lines 76 - 82.

val b2 = view.findViewById<Button>(R.id.navigate_action_button)
b2.setOnClickListener {
    // PROBLEM: HomeFragmentDirections isn't recognized.
    val action = HomeFragmentDirections.nextAction()
    // PROBLEM: results in Unresolved reference: flowStepNumber
    // action.flowStepNumber = 1
    findNavController().navigate(action)
}

I know what the documentation says & I know that class HomeFragmentDirections is being generated by the plugin & is located at app/build/generated/source/navigation-args/debug/code/example/android/codelabs/navigation, but it is not recognized by AS.

I also know that this did work pre-v2 of the plugin...but it's not working now & I can't even get a simple example to behave as expected.

Any ideas on what's wrong?

BACKGROUND

I'm using AS 3.5 on MacOS Mojave, 10.14.6.

Project build.gradle dependencies:

classpath 'com.android.tools.build:gradle:3.5.0'
classpath "androidx.navigation:navigation-safe-args-gradle-plugin:2.1.0"
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.3.50"

App build.gradle file:

apply plugin: 'androidx.navigation.safeargs.kotlin'

dependencies {
  // Navigation
  def nav_version = "2.1.0"
  implementation "androidx.navigation:navigation-fragment-ktx:$nav_version"
  implementation "androidx.navigation:navigation-ui-ktx:$nav_version"
}

Answer 1

The reason Android Studio/Lint wasn't "seeing" these classes was BIAD (b/c I'm a dummy).

I excluded the build folder in the Project Panel via Preferences > Editor > File Types > Ignore files and folders.

In any event, removing the build folder from Ignore files and folders did the trick.

Answer 2

Select the Project view in the project tab, so you can see the actual folders. You'll notice the app/build folder is oranged out, which means it's being excluded. Simply right click > Mark directory as > Cancel exclusion, then right click again > Mark directory as > Sources root. The folder will be blued out like the java folder and AS should recognize the generated classes.

Although I'm not sure I believe all the code you're gonna use is actually in app/build/generated, so you could be more specific marking that one as the sources root instead. So it should look something like this.