Fix kotlin nullable errors in perftests

Fix kotlin nullable errors that were exposed by setting the retention
of android.annotation.NonNull and android.annotation.Nullable to
class retention.

Bug: 294110802
Test: builds
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:2522501d5b4b4eab8d20986aa1c4b6ed36640211)
Merged-In: Icfec5d0e20b534d7af9aeb1b539a711db76d5e5c
Change-Id: Icfec5d0e20b534d7af9aeb1b539a711db76d5e5c

apct-tests/perftests/core/src/android/input/MotionPredictorBenchmark.kt

@@ -130,7 +130,7 @@ class MotionPredictorBenchmark {
                 eventTime, ACTION_MOVE, /*x=*/eventPosition, /*y=*/eventPosition)
             predictor.record(moveEvent)
             val predictionTime = eventTime + eventInterval
-            val predicted = predictor.predict(predictionTime.toNanos())
+            val predicted = checkNotNull(predictor.predict(predictionTime.toNanos()))
             assertTrue(predicted.eventTime <= (predictionTime + offset).toMillis())
         }
     }