Spring Security OAuth 2 client customize User Info Endpoint Requests

Question

I am trying to implement a server client to authenticate to the Etsy API OAuth2 to get and manage store details.

Authentication works, but I am having issues with the user info endpoint call.

In the Etsy API the only 'appropriate' end point is getUser.

Two issues:

1. The getUser expects the Etsy UserId /v3/application/users/{user_id}, all the examples I have seen have a static uri. Is it possible to dynamically provide this?

2. The Esty getUser expects a GET request and as far as I can tell the default user info call is a POST. Can be configured?

Questions:

Does this require a custom ClientRegistration class to adapt the user info endpoint request to work with the Etsy API endpoint?

If so, is there an example starting point for implementing this functionality?

Details:

API documentation, Authentication:
https://developers.etsy.com/documentation/reference#section/Authentication

Note: The {user_id} is prefixed to the access_token in the authentication response. The response in theory should be parsed and the {user_id} used in the uri for user info request.

API documentation, getUser:
https://developers.etsy.com/documentation/reference#operation/getUser

Properties:

spring.security.oauth2.client.registration.etsy.client-id=REDACTED
spring.security.oauth2.client.registration.etsy.client-secret=REDACTED
spring.security.oauth2.client.registration.etsy.client-authentication-method=none
spring.security.oauth2.client.registration.etsy.provider=etsy
spring.security.oauth2.client.registration.etsy.authorization-grant-type=authorization_code
spring.security.oauth2.client.registration.etsy.redirect-uri={baseUrl}/{action}/oauth2/code/{registrationId}
spring.security.oauth2.client.registration.etsy.scope=transactions_r

spring.security.oauth2.client.provider.etsy.user-info-authentication-method=form
spring.security.oauth2.client.provider.etsy.user-name-attribute=user_id
# Hard coded the user id, XXXXXXX, to prove the end point is reached, but the POST request fails (Etsy endpoint expects a GET)
spring.security.oauth2.client.provider.etsy.user-info-uri=https://openapi.etsy.com/v3/application/users/XXXXXXX
spring.security.oauth2.client.provider.etsy.token-uri=https://openapi.etsy.com/v3/public/oauth/token
spring.security.oauth2.client.provider.etsy.authorization-uri=https://www.etsy.com/oauth/connect