Add constant NO_LIKE_COUNT to CommentsInfoItem

Author: TobiGr

extractor/src/main/java/org/schabi/newpipe/extractor/comments/CommentsInfoItem.java

@@ -22,6 +22,7 @@ public class CommentsInfoItem extends InfoItem {
     private boolean pinned;
     private int streamPosition;
 
+    public static final int NO_LIKE_COUNT = -1;
     public static final int NO_STREAM_POSITION = -1;
 
     public CommentsInfoItem(int serviceId, String url, String name) {
@@ -85,6 +86,10 @@ public void setUploadDate(@Nullable DateWrapper uploadDate) {
         this.uploadDate = uploadDate;
     }
 
+    /**
+     * @return the comment's like count
+     *         or {@link CommentsInfoItem#NO_LIKE_COUNT} if it is unavailable
+     */
     public int getLikeCount() {
         return likeCount;
     }

extractor/src/main/java/org/schabi/newpipe/extractor/comments/CommentsInfoItemExtractor.java

@@ -12,15 +12,20 @@
 public interface CommentsInfoItemExtractor extends InfoItemExtractor {
 
     /**
-     * Return the like count of the comment, or -1 if it's unavailable
+     * Return the like count of the comment,
+     * or {@link CommentsInfoItem#NO_LIKE_COUNT} if it is unavailable.
+     *
      * <br>
+     *
      * NOTE: Currently only implemented for YT {@link YoutubeCommentsInfoItemExtractor#getLikeCount()}
      * with limitations (only approximate like count is returned)
      *
      * @see StreamExtractor#getLikeCount()
+     * @return the comment's like count
+     * or {@link CommentsInfoItem#NO_LIKE_COUNT} if it is unavailable
      */
     default int getLikeCount() throws ParsingException {
-        return -1;
+        return CommentsInfoItem.NO_LIKE_COUNT;
     }
 
     /**