Commission Implementing Regulation (EU) 2017/454 of 15 March 2017 withdrawing the acceptance of the undertaking for four exporting producers under Implementing Decision 2013/707/EU confirming the acceptance of an undertaking offered in connection with the anti-dumping and anti-subsidy proceedings concerning imports of crystalline silicon photovoltaic modules and key components (i.e. cells) originating in or consigned from the People's Republic of China for the period of application of definitive measures