Configure basic auth for /oauth/token - oauth-2.0

Question

I want to implement token refresh for OAuth2 using Spring Cloud.
I can create token by sending request to /oauth/token using this payload:
curl --location --request POST 'http://localhost:8080/engine/oauth/token' \
--header 'Authorization: Basic YWRtaW46cXdlcnR5' \
--form 'username=admin' \
--form 'password=qwerty' \
--form 'grant_type=password' \
--form 'scope=read'
But for refresh token the same path /oauth/token is used. I need to send also username and password into the header 'Authorization: Basic YWRtaW46cXdlcnR5'which I don't have them. I can create a new token using using refresh token with this payload:
curl --location --request POST 'http://localhost:8080/engine/oauth/token' \
--header 'Authorization: Basic YWRtaW46cXdlcnR5' \
--form 'grant_type=refresh_token' \
--form 'scope=read' \
--form 'refresh_token=....'
Do you know how this issue can be solved?
Github code

Answer 1

The refresh token grant message does not need an Authorization header. Try removing it and sending client_id as a form parameter instead. You may also need to configure the offline_access scope for token refresh to work.
The last I remember though, token refresh is not supposed to be supported for ROPC, though that behaviour may not be the same for all providers.
Finally, be aware that ROPG is not really recommended if you have better options. This post summarises the issues.
If you can summarise your usage scenario I may be able to recommend a better alternative.