Change error log in update OAuth2 cache entry

[kasthuriraajan]

Description:
Change the error log message in an appropriate way.

Describe your problem(s)
Currently it shows error message as "Failed to access 'refreshToken' property from the JSON " along with the JSON property which has access token and scopes. But at some cases, there will not be a refresh_token property . In that cases this error log is inappropriate.

Describe your solution(s)
Change this error log as an appropriate message or a warning log message. As access token is sensitive one, we need to hide that from printing in log message.

Suggested Labels (optional):
module/oauth2 , type/improvement

Suggested Assignees (optional):
Chanaka Lakmal