Fix HiddenTypedefConstant Metalava error on PlaybackException

This is done by removing the `@FieldNumber` IntDef completely. It's not
really adding much value anyway, because it's `open` so there's no real
enforcement to prevent passing 'incorrect' values.

#minor-release

PiperOrigin-RevId: 452108972

library/common/src/main/java/com/google/android/exoplayer2/PlaybackException.java

@@ -397,35 +397,14 @@ public boolean errorInfoEquals(@Nullable PlaybackException other) {
 
   // Bundleable implementation.
 
-  /**
-   * Identifiers for fields in a {@link Bundle} which represents a playback exception. Subclasses
-   * may use {@link #FIELD_CUSTOM_ID_BASE} to generate more keys using {@link #keyForField(int)}.
-   *
-   * <p>Note: Changes to the Bundleable implementation must be backwards compatible, so as to avoid
-   * breaking communication across different Bundleable implementation versions.
-   */
-  @Documented
-  @Retention(RetentionPolicy.SOURCE)
-  @Target(TYPE_USE)
-  @IntDef(
-      open = true,
-      value = {
-        FIELD_INT_ERROR_CODE,
-        FIELD_LONG_TIMESTAMP_MS,
-        FIELD_STRING_MESSAGE,
-        FIELD_STRING_CAUSE_CLASS_NAME,
-        FIELD_STRING_CAUSE_MESSAGE,
-      })
-  protected @interface FieldNumber {}
-
   private static final int FIELD_INT_ERROR_CODE = 0;
   private static final int FIELD_LONG_TIMESTAMP_MS = 1;
   private static final int FIELD_STRING_MESSAGE = 2;
   private static final int FIELD_STRING_CAUSE_CLASS_NAME = 3;
   private static final int FIELD_STRING_CAUSE_MESSAGE = 4;
 
   /**
-   * Defines a minimum field id value for subclasses to use when implementing {@link #toBundle()}
+   * Defines a minimum field ID value for subclasses to use when implementing {@link #toBundle()}
    * and {@link Bundleable.Creator}.
    *
    * <p>Subclasses should obtain their {@link Bundle Bundle's} field keys by applying a non-negative
@@ -452,10 +431,13 @@ public Bundle toBundle() {
   }
 
   /**
-   * Converts the given {@link FieldNumber} to a string which can be used as a field key when
-   * implementing {@link #toBundle()} and {@link Bundleable.Creator}.
+   * Converts the given field number to a string which can be used as a field key when implementing
+   * {@link #toBundle()} and {@link Bundleable.Creator}.
+   *
+   * <p>Subclasses should use {@code field} values greater than or equal to {@link
+   * #FIELD_CUSTOM_ID_BASE}.
    */
-  protected static String keyForField(@FieldNumber int field) {
+  protected static String keyForField(int field) {
     return Integer.toString(field, Character.MAX_RADIX);
   }