public function getRefreshToken()
    {
        if (is_string($this->refresh_token) && $this->isValidToken() ){

            $this->refreshToken = $this->token_type . ' ' . $this->refresh_token;

            return $this->refreshToken;
        }

        return false;
    }
public function getRefreshToken()
    {
        if (is_string($this->refresh_token) && $this->isValidToken() ){

            $this->refreshToken = $this->token_type . ' ' . $this->refresh_token;

            return $this->refreshToken;
        }

        return false;
    }
public function getRefreshToken ( ) { if ( is_string ( $ this -> refresh_token ) && $ this -> isValidToken ( ) ) { $ this -> refreshToken = $ this -> token_type . ' ' . $ this -> refresh_token ; return $ this -> refreshToken ; } return false ; }
Return the Refresh Token, if available and valid
@return string
Return the Refresh Token if available and valid