Refresh Token

[faw872]

Anyone using this or later forks needs to know this. You need to be able to use the refresh token so you can keep getting access tokens. For Example:
$refreshToken = 'sfdsafdsagsdfgdfsads';
$provider = new KevinEm\OAuth2\Client\AdobeSign([...........;

$newAccessToken = $provider->getAccessToken('refresh_token', [
'refresh_token' => $refreshToken
]);
I was unable to get a refresh token until I added "/v2" to the url in adobesign.php
public function getBaseRefreshTokenUrl()
{
return "https://$this->dataCenter.echosign.com/oauth/v2/refresh";
}