Suppress warnings emitted by Checker Framework version 2.11.1

More information:
https://docs.google.com/document/d/16tpK6aXqN68PvTyvt4siM-m7f0NXi_8xEeitLDzr8xY/edit?usp=sharing

Tested:
    TAP --sample ran all affected tests and none failed
    http://test/OCL:278915274:BASE:278884711:1573074344615:a6701677
PiperOrigin-RevId: 279080514

extensions/flac/src/main/java/com/google/android/exoplayer2/ext/flac/FlacDecoderJni.java

@@ -51,6 +51,12 @@ import java.nio.ByteBuffer;
   @Nullable private byte[] tempBuffer;
   private boolean endOfExtractorInput;
 
+  // the constructor does not initialize fields: tempBuffer
+  // call to flacInit() not allowed on the given receiver.
+  @SuppressWarnings({
+    "nullness:initialization.fields.uninitialized",
+    "nullness:method.invocation.invalid"
+  })
   public FlacDecoderJni() throws FlacDecoderException {
     if (!FlacLibrary.isAvailable()) {
       throw new FlacDecoderException("Failed to load decoder native libraries.");

library/ui/src/main/java/com/google/android/exoplayer2/ui/DefaultTimeBar.java

@@ -239,7 +239,11 @@ public class DefaultTimeBar extends View implements TimeBar {
   }
 
   // Suppress warnings due to usage of View methods in the constructor.
-  @SuppressWarnings("nullness:method.invocation.invalid")
+  // the constructor does not initialize fields: adGroupTimesMs, playedAdGroups
+  @SuppressWarnings({
+    "nullness:method.invocation.invalid",
+    "nullness:initialization.fields.uninitialized"
+  })
   public DefaultTimeBar(
       Context context,
       @Nullable AttributeSet attrs,