Fix nullness checker warnings

PiperOrigin-RevId: 307570994

library/core/src/main/java/com/google/android/exoplayer2/source/MergingMediaPeriod.java

@@ -158,8 +158,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     // Copy the new streams back into the streams array.
     System.arraycopy(newStreams, 0, streams, 0, newStreams.length);
     // Update the local state.
-    enabledPeriods = new MediaPeriod[enabledPeriodsList.size()];
-    enabledPeriodsList.toArray(enabledPeriods);
+    enabledPeriods = enabledPeriodsList.toArray(new MediaPeriod[0]);
     compositeSequenceableLoader =
         compositeSequenceableLoaderFactory.createCompositeSequenceableLoader(enabledPeriods);
     return positionUs;

library/core/src/main/java/com/google/android/exoplayer2/text/subrip/SubripDecoder.java

@@ -135,8 +135,7 @@ public final class SubripDecoder extends SimpleSubtitleDecoder {
       cues.add(Cue.EMPTY);
     }
 
-    Cue[] cuesArray = new Cue[cues.size()];
-    cues.toArray(cuesArray);
+    Cue[] cuesArray = cues.toArray(new Cue[0]);
     long[] cueTimesUsArray = cueTimesUs.toArray();
     return new SubripSubtitle(cuesArray, cueTimesUsArray);
   }