Extract YouTube playlist description

extractor/src/main/java/org/schabi/newpipe/extractor/playlist/PlaylistExtractor.java

@@ -21,6 +21,8 @@ public abstract class PlaylistExtractor extends ListExtractor<StreamInfoItem> {
 
     public abstract long getStreamCount() throws ParsingException;
 
+    public abstract String getDescription() throws ParsingException;
+
     @Nonnull
     public String getThumbnailUrl() throws ParsingException {
         return "";

extractor/src/main/java/org/schabi/newpipe/extractor/services/bandcamp/extractors/BandcampPlaylistExtractor.java

@@ -108,6 +108,11 @@ public class BandcampPlaylistExtractor extends PlaylistExtractor {
         return trackInfo.size();
     }
 
+    @Override
+    public String getDescription() throws ParsingException {
+        return "";
+    }
+
     @Nonnull
     @Override
     public InfoItemsPage<StreamInfoItem> getInitialPage() throws ExtractionException {

extractor/src/main/java/org/schabi/newpipe/extractor/services/peertube/extractors/PeertubePlaylistExtractor.java

@@ -65,6 +65,11 @@ public class PeertubePlaylistExtractor extends PlaylistExtractor {
         return playlistInfo.getLong("videosLength");
     }
 
+    @Override
+    public String getDescription() throws ParsingException {
+        return "";
+    }
+
     @Nonnull
     @Override
     public String getSubChannelName() {

extractor/src/main/java/org/schabi/newpipe/extractor/services/soundcloud/extractors/SoundcloudPlaylistExtractor.java

@@ -118,6 +118,11 @@ public class SoundcloudPlaylistExtractor extends PlaylistExtractor {
         return playlist.getLong("track_count");
     }
 
+    @Override
+    public String getDescription() throws ParsingException {
+        return "";
+    }
+
     @Nonnull
     @Override
     public InfoItemsPage<StreamInfoItem> getInitialPage() {

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeMixPlaylistExtractor.java

@@ -169,6 +169,11 @@ public class YoutubeMixPlaylistExtractor extends PlaylistExtractor {
         return ListExtractor.ITEM_COUNT_INFINITE;
     }
 
+    @Override
+    public String getDescription() throws ParsingException {
+        return "";
+    }
+
     @Nonnull
     @Override
     public InfoItemsPage<StreamInfoItem> getInitialPage()

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubePlaylistExtractor.java

@@ -294,6 +294,11 @@ public class YoutubePlaylistExtractor extends PlaylistExtractor {
         return ITEM_COUNT_UNKNOWN;
     }
 
+    @Override
+    public String getDescription() throws ParsingException {
+        return getTextFromObject(getPlaylistInfo().getObject("description"));
+    }
+
     @Nonnull
     @Override
     public InfoItemsPage<StreamInfoItem> getInitialPage() throws IOException, ExtractionException {