@Override
 public boolean isEmpty() {
   this.requiredEnabled();
   RootData<K, V> rootData = this.getRootData();
   if (0 == rootData.visionallyReadSize()) {
     return true;
   }
   rootData.load();
   return this.getBase().isEmpty();
 }
 @Override
 public int size() {
   this.requiredEnabled();
   RootData<K, V> rootData = this.getRootData();
   if (this.<AbstractLazyXMap<K, V>>getParentMap().getParent() == null) {
     int size = rootData.visionallyReadSize();
     if (size != -1) {
       return size;
     }
   }
   rootData.load();
   return this.getBase().size();
 }