code: public List<ExtensionElement> getExtendedInfoAsList() {
          List<ExtensionElement> res = null;
          if (extendedInfo != null) {
              res = new ArrayList<>(1);
              res.add(extendedInfo);
          }
          return res;
      }
docs: Returns the data form as List of PacketExtensions, or null if no data form is set.
  This representation is needed by some classes (e.g. EntityCapsManager, NodeInformationProvider)
  
  @return the data form as List of PacketExtensions