The specifications of the following API has been changed as shown below as announced on August 31.
[API]
https://api.line.me/v1/oauth/accessToken
[Changes]
The expires_in value will be displayed in seconds instead of milliseconds.
It will be possible to refresh tokens before they expire. Currently, an error will occur when you refresh a token before it has expired.
[Reason]
To comply with OAuth2 specifications.
[Date and Time]
16:00 on September 14, 2015 (Finished)