Fix Javadoc errors

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=195555915

library/core/src/main/java/com/google/android/exoplayer2/offline/DownloadHelper.java

@@ -97,7 +97,7 @@ public abstract class DownloadHelper {
    * completes.
    *
    * @param periodIndex The period index.
-   * @return The track groups for the period. May be {@link TrackGroupArray.EMPTY} for single stream
+   * @return The track groups for the period. May be {@link TrackGroupArray#EMPTY} for single stream
    *     content.
    */
   public abstract TrackGroupArray getTrackGroups(int periodIndex);

library/core/src/main/java/com/google/android/exoplayer2/trackselection/MappingTrackSelector.java

@@ -62,15 +62,15 @@ public abstract class MappingTrackSelector extends TrackSelector {
     /**
      * The renderer has tracks mapped to it and at least one is of a supported type, but all such
      * tracks exceed the renderer's capabilities. In other words, {@link #getTrackSupport(int, int,
-     * int)} returns {@link RendererCapabilities##FORMAT_EXCEEDS_CAPABILITIES} for at least one
+     * int)} returns {@link RendererCapabilities#FORMAT_EXCEEDS_CAPABILITIES} for at least one
      * track mapped to the renderer, but does not return {@link
-     * RendererCapabilities##FORMAT_HANDLED} for any tracks mapped to the renderer.
+     * RendererCapabilities#FORMAT_HANDLED} for any tracks mapped to the renderer.
      */
     public static final int RENDERER_SUPPORT_EXCEEDS_CAPABILITIES_TRACKS = 2;
     /**
      * The renderer has tracks mapped to it, and at least one such track is playable. In other
      * words, {@link #getTrackSupport(int, int, int)} returns {@link
-     * RendererCapabilities##FORMAT_HANDLED} for at least one track mapped to the renderer.
+     * RendererCapabilities#FORMAT_HANDLED} for at least one track mapped to the renderer.
      */
     public static final int RENDERER_SUPPORT_PLAYABLE_TRACKS = 3;