fixup: add implementation to base collectors and extractor

Author: wispl

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

@@ -175,8 +175,8 @@ public List<Image> getThumbnails() throws ParsingException {
         }
     }
 
-    @Nonnull
-    public String getPlaylist() {
+    @Override
+    public String getPlaylistId() throws ParsingException {
         if (searchType.equals(MUSIC_SONGS)) {
             for (final Object item : descriptionElements) {
                 final JsonObject browseEndpoint = ((JsonObject) item)

extractor/src/main/java/org/schabi/newpipe/extractor/stream/StreamInfoItem.java

@@ -37,6 +37,7 @@ public class StreamInfoItem extends InfoItem {
     private String uploaderName;
     private String shortDescription;
     private String textualUploadDate;
+    private String playlistId;
     @Nullable
     private DateWrapper uploadDate;
     private long viewCount = -1;
@@ -120,6 +121,14 @@ public void setTextualUploadDate(final String textualUploadDate) {
         this.textualUploadDate = textualUploadDate;
     }
 
+    public String getPlaylistId() {
+        return playlistId;
+    }
+
+    public void setPlaylistId(final String playlistId) {
+        this.playlistId = playlistId;
+    }
+
     @Nullable
     public DateWrapper getUploadDate() {
         return uploadDate;

extractor/src/main/java/org/schabi/newpipe/extractor/stream/StreamInfoItemExtractor.java

@@ -162,4 +162,14 @@ default boolean isShortFormContent() throws ParsingException {
     default ContentAvailability getContentAvailability() throws ParsingException {
         return ContentAvailability.UNKNOWN;
     }
+
+    /**
+     * Gets the playlist id of the stream item.
+     *
+     * @return the playlist id of the stream item.
+     * @throws ParsingException if there is an error in the extraction
+     */
+    default String getPlaylistId() throws ParsingException {
+	return "";
+    }
 }

extractor/src/main/java/org/schabi/newpipe/extractor/stream/StreamInfoItemsCollector.java

@@ -108,6 +108,11 @@ public StreamInfoItem extract(final StreamInfoItemExtractor extractor) throws Pa
         } catch (final Exception e) {
             addError(e);
         }
+        try {
+            resultItem.setPlaylistId(extractor.getPlaylistId());
+        } catch (final Exception e) {
+            addError(e);
+        }
 
         return resultItem;
     }