code: public Set getChildrenNames(String fqn) {
          Node n=findNode(fqn);
          Map m;
  
          if(n == null) return null;
          m=n.getChildren();
          if(m != null)
              return m.keySet();
          else
              return null;
      }
docs: Returns all children of a given node
  @param fqn The fully qualified name of the node
  @return Set A list of child names (as Strings)