Changes to Exchange a code, refresh token, or subject token for an access token

added the non-success response with the status 429

added the media type application/x-www-form-urlencoded to the request body

added the new invalid_request enum value to the error response property for the response status 400

added the new invalid_scope enum value to the error response property for the response status 400

added the new invalid_target enum value to the error response property for the response status 400

added the new optional request property requested_token_type

added the new optional request property subject_token

added the new optional request property subject_token_type

added the new urn:ietf:params:oauth:grant-type:token-exchange enum value to the request property grant_type

added the optional property issued_token_type to the response with the 200 status

endpoint added