Fix nullable annotations

Author: Isira-Seneviratne

extractor/src/main/java/org/schabi/newpipe/extractor/services/media_ccc/extractors/MediaCCCStreamExtractor.java

@@ -36,6 +36,7 @@
 import java.util.Locale;
 
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 
 public class MediaCCCStreamExtractor extends StreamExtractor {
     private JsonObject data;
@@ -45,13 +46,13 @@ public MediaCCCStreamExtractor(final StreamingService service, final LinkHandler
         super(service, linkHandler);
     }
 
-    @Nonnull
+    @Nullable
     @Override
     public String getTextualUploadDate() {
         return data.getString("release_date");
     }
 
-    @Nonnull
+    @Nullable
     @Override
     public DateWrapper getUploadDate() throws ParsingException {
         return DateWrapper.fromOffsetDateTime(getTextualUploadDate());