code: @Override
      public void backward() {
          Tensor tmp1 = new Tensor(yAdj); // copy
          tmp1.multiply(weightX);
          modInX.getOutputAdj().elemAdd(tmp1);
  
          Tensor tmp2 = new Tensor(yAdj); // copy
          tmp2.multiply(weightW);
          modInW.getOutputAdj().elemAdd(tmp2);
      }
docs: Backward pass:
  dG/dx_i += dG/dy_i dy_i/dx_i = dG/dy_i \lambda
  dG/dw_i += dG/dy_i dy_i/dw_i = dG/dy_i \gamma