as32: Kapt: 'kapt.kotlin.generated' is not marked as source root in Android Studio (#KT-24449)

plugins/kapt3/kapt3-idea/src/org/jetbrains/kotlin/kapt/idea/KaptProjectResolverExtension.kt.as32

@@ -16,6 +16,7 @@
 
 package org.jetbrains.kotlin.kapt.idea
 
+import com.android.ide.common.gradle.model.IdeBaseArtifact
 import com.android.tools.idea.gradle.project.model.AndroidModuleModel
 import com.intellij.openapi.diagnostic.Logger
 import com.intellij.openapi.externalSystem.model.DataNode
@@ -117,15 +118,9 @@ class KaptProjectResolverExtension : AbstractProjectResolverExtension() {
             val androidModel = androidModelAny.data as? AndroidModuleModel ?: return
             val variant = androidModel.findVariantByName(sourceSet.sourceSetName) ?: return
 
-            androidModel.registerExtraGeneratedSourceFolder(generatedKotlinSources)
-
-            // TODO remove this when IDEA eventually migrate to the newer Android plugin
-            try {
-                variant.mainArtifact.generatedSourceFolders += generatedKotlinSources
-            } catch (e: Throwable) {
-                // There was an error being thrown here, but the code above doesn't work for the newer versions of Android Studio 3
-                // (generatedSourceFolders returns a wrapped unmodifiable list), and the thrown exception breaks the import.
-                // The error will be moved back when I find a work-around for AS3.
+            val mainArtifact = variant.mainArtifact
+            if (mainArtifact is IdeBaseArtifact) {
+                mainArtifact.addGeneratedSourceFolder(generatedKotlinSources)
             }
         }
     }