How to add attribures to a node since Attribute_buffer is a vitual class?

How to add additional information to a simple node data, it seems that it lacks interfaces about it.

Start by reviewing the node data interfaces and the Attribute_buffer abstraction mentioned in the issue. Determine whether the project already exposes a supported extension point for additional node information; done should mean a clearly defined way to add attributes, with the relevant interface behavior documented or tested.

Written by the indexing model from the issue text.