docs: long storeSpaceForAdd() {
          return ConcurrentSubList.maximumSerializedSize() // List header
                 + 3 * ConcurrentSubList.Link.maximumSerializedSize() // Current,Previous,Next links  
                 + 4 * owningToken.objectStore.getAddSpaceOverhead() // Store overhead for all of the above.
                 + storeSpaceForRemove(); // In case we backoutTheAdd.
      }