docs: public void _put(String fqn, HashMap data) {
          Node n;
          StringHolder child_name=new StringHolder();
          boolean child_exists=false;
  
          if(fqn == null) return;
          n=findParentNode(fqn, child_name, true); // create all nodes if they don't exist
          if(child_name.getValue() != null) {
              child_exists=n.childExists(child_name.getValue());
              n.createChild(child_name.getValue(), fqn, n, data);
          }
          else {
              child_exists=true;
              n.setData(data);
          }
          if(child_exists)
              notifyNodeModified(fqn);
          else
              notifyNodeAdded(fqn);
      }