m = 5.3
n1 = 1.0
n2 = 1.0
D = 1.0e-3
k = 22
hcubature(x->(2*x[1]^3*(n1+n2*cos(2*x[2]))/sqrt((x[1]^2-2*m)^2+(2*x[1]*D)^2*(n1^2+n2^2)+2*n1*n2*cos(2*x[2]))),[0.0,0.0],[k,pi])

#setfield! immutable struct of type IntegrandData cannot be changed