Add some missing nullness annotations

PiperOrigin-RevId: 292910310

library/core/src/main/java/com/google/android/exoplayer2/mediacodec/MediaCodecRenderer.java

@@ -136,8 +136,8 @@ public abstract class MediaCodecRenderer extends BaseRenderer {
      */
     @Nullable public final DecoderInitializationException fallbackDecoderInitializationException;
 
-    public DecoderInitializationException(Format format, Throwable cause,
-        boolean secureDecoderRequired, int errorCode) {
+    public DecoderInitializationException(
+        Format format, @Nullable Throwable cause, boolean secureDecoderRequired, int errorCode) {
       this(
           "Decoder init failed: [" + errorCode + "], " + format,
           cause,
@@ -150,7 +150,7 @@ public abstract class MediaCodecRenderer extends BaseRenderer {
 
     public DecoderInitializationException(
         Format format,
-        Throwable cause,
+        @Nullable Throwable cause,
         boolean secureDecoderRequired,
         MediaCodecInfo mediaCodecInfo) {
       this(
@@ -165,7 +165,7 @@ public abstract class MediaCodecRenderer extends BaseRenderer {
 
     private DecoderInitializationException(
         String message,
-        Throwable cause,
+        @Nullable Throwable cause,
         String mimeType,
         boolean secureDecoderRequired,
         @Nullable MediaCodecInfo mediaCodecInfo,
@@ -193,7 +193,8 @@ public abstract class MediaCodecRenderer extends BaseRenderer {
     }
 
     @RequiresApi(21)
-    private static String getDiagnosticInfoV21(Throwable cause) {
+    @Nullable
+    private static String getDiagnosticInfoV21(@Nullable Throwable cause) {
       if (cause instanceof CodecException) {
         return ((CodecException) cause).getDiagnosticInfo();
       }