Fix Javadoc generation

build.gradle

@@ -48,6 +48,12 @@ task aggregatedJavadocs(type: Javadoc, group: 'Documentation') {
     // options.memberLevel = JavadocMemberLevel.PRIVATE
     options.links 'https://docs.oracle.com/javase/8/docs/api/'
     options.encoding 'UTF-8'
+    // Fixes unknown tag @implNote; the other two were added precautionary
+    options.tags = [
+            "apiNote:a:API Note:",
+            "implSpec:a:Implementation Requirements:",
+            "implNote:a:Implementation Note:"
+            ]
 
     subprojects.each { project ->
         project.tasks.withType(Javadoc).each { javadocTask ->

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

@@ -12,8 +12,8 @@ import javax.annotation.Nullable;
 public interface CommentsInfoItemExtractor extends InfoItemExtractor {
 
     /**
-     * Return the like count of the comment, or -1 if it's unavailable<br/>
+     * Return the like count of the comment, or -1 if it's unavailable<
-     *
+     * <br>
      * NOTE: Currently only implemented for YT {@link YoutubeCommentsInfoItemExtractor#getLikeCount()}
      * with limitations (only approximate like count is returned)
      *
@@ -24,8 +24,8 @@ public interface CommentsInfoItemExtractor extends InfoItemExtractor {
     }
 
     /**
-     * The unmodified like count given by the service<br/>
+     * The unmodified like count given by the service
-     *
+     * <br>
      * It may be language dependent
      */
     default String getTextualLikeCount() throws ParsingException {

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

@@ -72,10 +72,10 @@ public class YoutubeCommentsInfoItemExtractor implements CommentsInfoItemExtract
     }
 
     /**
-     * @implNote The method is parsing internally a localized string.<br/>
+     * @implNote The method is parsing internally a localized string.<br>
      * <ul>
      *     <li>
-     *         More than >1k likes will result in an inaccurate number
+     *         More than 1k likes will result in an inaccurate number
      *     </li>
      *     <li>
      *         This will fail for other languages than English.
@@ -84,7 +84,7 @@ public class YoutubeCommentsInfoItemExtractor implements CommentsInfoItemExtract
      *         everything will work fine.
      *      </li>
      * </ul>
-     * <br/>
+     * <br>
      * Consider using {@link #getTextualLikeCount()}
      */
     @Override