Fix compilation warning after bump kotlin-gradle-plugin from 1.6.0 to 1.6.21

matrix-sdk-android/build.gradle

@@ -98,6 +98,9 @@ android {
         freeCompilerArgs += [
                 // Disabled for now, there are too many errors. Could be handled in another dedicated PR
                 // '-Xexplicit-api=strict', // or warning
+                "-Xopt-in=kotlin.RequiresOptIn",
+                // Opt in for kotlinx.coroutines.FlowPreview
+                "-Xopt-in=kotlinx.coroutines.FlowPreview",
         ]
     }
 

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/network/parsing/CheckNumberType.kt

@@ -33,7 +33,7 @@ internal interface CheckNumberType {
     companion object {
         val JSON_ADAPTER_FACTORY = object : JsonAdapter.Factory {
             @Nullable
-            override fun create(type: Type, annotations: Set<Annotation?>?, moshi: Moshi): JsonAdapter<*>? {
+            override fun create(type: Type, annotations: Set<Annotation>, moshi: Moshi): JsonAdapter<*>? {
                 if (type !== Any::class.java) {
                     return null
                 }

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/timeline/DefaultTimeline.kt

@@ -291,7 +291,6 @@ internal class DefaultTimeline(
         }
     }
 
-    @Suppress("EXPERIMENTAL_API_USAGE")
     private fun listenToPostSnapshotSignals() {
         postSnapshotSignalFlow
                 .sample(150)