"EstimateGyroBias",why ignore extrinsic parameters beween IMU and Lidar?

[ZzJiachenchen]

why in function "EstimateGyroBias", when estimating gyro bias of IMU, there can ignore the extrinsic parameters beween IMU and Lidar?

 Eigen::Quaterniond q_ij(laser_trans_i.second.transform.rot.conjugate() * laser_trans_j.second.transform.rot);

tmp_A = laser_trans_j.second.pre_integration->jacobian_.template block<3, 3>(O_R, O_BG);
 /// Jacobian of dr12_bg

tmp_b = 2 * (laser_trans_j.second.pre_integration->delta_q_.conjugate() * q_ij).vec();
 /// 2*vec(IMU_ij^T * q_ij)

Why tmp_b is not :

2*vec(IMU_ij^T *(rbl* q_ij* rlb))

Thanks a lot!