Tinjauan yuridis terhadap perjanjian pihak swasta dalam bahasa Inggris yang dinyatakan batal demi hukum: studi kasus putusan Mahkamah Agung nomor 601 K/PDT/2015 = Juridicial review of foreign language contract were invalidated due to laws and regulations: a case study of decision number 601 K/PDT/2015