Doc Feedback: extension Client Authentication Handler relevance

[MaxLiv]

Location : https://is.docs.wso2.com/en/latest/learn/extension-points-for-oauth/
Description: Is Client Authentication Handler paragraph steel relevant? First, "Configuration" part show xml instead toml, then I could not find any mention of BasicAuthClientAuthHandler in config files. Also I looking using of BasicAuthClientAuthHandler in the AccessTokenIssuer code, but it seems does not using anymore there. So my question, can I extend Client Authentication Handler or this option no longer available?