protected void copyPropertiesToResult(TreeNode<QueryInfo> queryTree, TreeNode<Set<String>> propertyTree) {
    for (TreeNode<QueryInfo> node : queryTree.getChildren()) {
      TreeNode<Set<String>> child = propertyTree.addChild(
          node.getObject().getProperties(), node.getName());
      copyPropertiesToResult(node, child);
    }
  }
Copies a tree of QueryInfo to a tree of Set<String>.
This is useful in {@link Renderer#finalizeProperties(TreeNode, boolean)} for converting
the passed in tree of query info to the return type which is a set of property names.

@param queryTree     source tree
@param propertyTree  target tree
ambari-server/src/main/java/org/apache/ambari/server/api/query/render/BaseRenderer.java