Hello everyone, we found a strange issue migrating from Kotlin 1.2.51 to 1.2.60 (always present with AGP 3.1.3, 3.1.4, 3.2.0-beta04 and 3.2.0-beta05, and android extensions plugin):

exception: java.lang.ClassCastException: java.util.Collections$UnmodifiableCollection cannot be cast to java.util.Set
    at org.jetbrains.kotlin.android.synthetic.AndroidComponentRegistrar.registerProjectComponents(AndroidComponentRegistrar.kt:154)
    at org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment.<init>(KotlinCoreEnvironment.kt:179)
    at org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment.<init>(KotlinCoreEnvironment.kt:117)
    at org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment$Companion.createForProduction(KotlinCoreEnvironment.kt:413)

I couldn't really find anything on the web, we tried to refactor away some problematic libraries like Guava, but no luck 😕

@myanmarking also had this problem Don’t know, does he solve it or not

I'll try with beta06 right now, I did not get an update so far

sorry, bet05, just mistyped

Thanks @gildor - I honestly have no idea on which other library can interfere with Kotlin 1.2.60

It’s not a library, it’s some error during build. Problem of Kotlin Plugin for Android

Are you using any annotation processor?

Looks like something related to android-extensions

@JoseF not in the module that crashes the build - @gildor I couldn't tell, we had the same feeling, but it's complex to pin point the source of the issue