Add DEVSIX reference to TODOs in tagging utilities for proper tags removal

DEVSIX-5472

Author: yulian-gaponenko

kernel/src/main/java/com/itextpdf/kernel/pdf/tagutils/TagStructureContext.java

@@ -643,7 +643,8 @@ private void removePageTagFromParent(IStructureNode pageTag, IStructureNode pare
                     removePageTagFromParent(structParent, parent.getParent());
                     PdfIndirectReference indRef = parentStructDict.getIndirectReference();
                     if (indRef != null) {
-                        // TODO how about possible references to structure element from refs or structure destination for instance?
+                        // TODO DEVSIX-5472 need to clean references to structure element from
+                        //  other structure elements /Ref entries and structure destinations
                         indRef.setFree();
                     }
                 }

kernel/src/main/java/com/itextpdf/kernel/pdf/tagutils/TagTreePointer.java

@@ -359,7 +359,8 @@ public TagTreePointer removeTag() {
 
         PdfIndirectReference indRef = currentStructElem.getPdfObject().getIndirectReference();
         if (indRef != null) {
-            // TODO how about possible references to structure element from refs or structure destination for instance?
+            // TODO DEVSIX-5472 need to clean references to structure element from
+            //  other structure elements /Ref entries and structure destinations
             indRef.setFree();
         }