The KLEVER Survey: spatially resolved metallicity maps and gradients in a sample of 1.2 < z < 2.5 lensed galaxies by Curti, M, Maiolino, R, Cirasuolo, M, Mannucci, F, Williams, RJ, Auger, M, Mercurio, A, Hayden-Pawson, C, Cresci, G, Marconi, A, Belfiore, F, Cappellari, M, Cicone, C, Cullen, F, Meneghetti, M, Ota, K, Peng, Y, Pettini, M, Swinbank, M, Troncoso, P