src/NexmoServiceProvider.php
protected function createPrivateKeyCredentials($key, $applicationId)
    {
        return new Client\Credentials\Keypair($this->loadPrivateKey($key), $applicationId);
    }
protected function createPrivateKeyCredentials($key, $applicationId)
    {
        return new Client\Credentials\Keypair($this->loadPrivateKey($key), $applicationId);
    }
protected function createPrivateKeyCredentials ( $ key , $ applicationId ) { return new Client \ Credentials \ Keypair ( $ this -> loadPrivateKey ( $ key ) , $ applicationId ) ; }
Create Keypair credentials for client.

@param string $key
@param string $applicationId

@return Client\Credentials\Keypair
Create Keypair credentials for client .