Keabsahan akta perjanjian pengikatan jual beli (PPJB) berkaitan dengan akta kuasa menjual dalam jual beli tanah: studi putusan Pengadilan Negeri Bandung nomor 387/Pdt.G/2017/PN.Bdg = The validity of the deed of sale and purchase agreement in relation to the deed of power of attorney to sell land: study of Bandung District Court's Decision number 387/Pdt.G/2017/PN.Bdg