oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/web/reactive/function/client/ServletOAuth2AuthorizedClientExchangeFilterFunction.java
public static Consumer<Map<String, Object>> authentication(Authentication authentication) {
		return attributes -> attributes.put(AUTHENTICATION_ATTR_NAME, authentication);
	}
public static Consumer<Map<String, Object>> authentication(Authentication authentication) {
		return attributes -> attributes.put(AUTHENTICATION_ATTR_NAME, authentication);
	}
Modifies the {@link ClientRequest#attributes()} to include the {@link Authentication} used to
look up and save the {@link OAuth2AuthorizedClient}. The value is defaulted in
{@link ServletOAuth2AuthorizedClientExchangeFilterFunction#defaultRequest()}

@param authentication the {@link Authentication} to use.
@return the {@link Consumer} to populate the attributes