Fix broken Javadoc

Issue: #2433

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=147355544

library/src/main/java/com/google/android/exoplayer2/audio/AudioTrack.java

@@ -840,7 +840,7 @@ public final class AudioTrack {
    * audio session id has changed. Enabling tunneling requires platform API version 21 onwards.
    *
    * @param tunnelingAudioSessionId The audio session id to use.
-   * @throws IllegalStateException Thrown if enabling tunneling on platform API version < 21.
+   * @throws IllegalStateException Thrown if enabling tunneling on platform API version &lt; 21.
    */
   public void enableTunnelingV21(int tunnelingAudioSessionId) {
     Assertions.checkState(Util.SDK_INT >= 21);

library/src/main/java/com/google/android/exoplayer2/drm/DefaultDrmSessionManager.java

@@ -280,6 +280,7 @@ public class DefaultDrmSessionManager<T extends ExoMediaCrypto> implements DrmSe
    * required.
    *
    * <p>{@code mode} must be one of these:
+   * <ul>
    * <li>{@link #MODE_PLAYBACK}: If {@code offlineLicenseKeySetId} is null, a streaming license is
    *     requested otherwise the offline license is restored.
    * <li>{@link #MODE_QUERY}: {@code offlineLicenseKeySetId} can not be null. The offline license
@@ -288,6 +289,7 @@ public class DefaultDrmSessionManager<T extends ExoMediaCrypto> implements DrmSe
    *     requested otherwise the offline license is renewed.
    * <li>{@link #MODE_RELEASE}: {@code offlineLicenseKeySetId} can not be null. The offline license
    *     is released.
+   * </ul>
    *
    * @param mode The mode to be set.
    * @param offlineLicenseKeySetId The key set id of the license to be used with the given mode.