Compiling error with gazebo-11

[aliciaji1993]

I am trying to catkin build velodyne_gazebo_plugins, but found several compiling errors:

/home/yufeng/ros_catkin_ws/src/velodyne_simulator/velodyne_gazebo_plugins/src/GazeboRosVelodyneLaser.cpp: In member function ‘virtual void gazebo::GazeboRosVelodyneLaser::Load(gazebo::sensors::SensorPtr, sdf::v9::ElementPtr)’:
/home/yufeng/ros_catkin_ws/src/velodyne_simulator/velodyne_gazebo_plugins/src/GazeboRosVelodyneLaser.cpp:98:31: error: ‘class gazebo::physics::World’ has no member named ‘GetSimTime’; did you mean ‘SetSimTime’?
   98 |   last_update_time_ = world_->GetSimTime();
      |                               ^~~~~~~~~~
      |                               SetSimTime
/home/yufeng/ros_catkin_ws/src/velodyne_simulator/velodyne_gazebo_plugins/src/GazeboRosVelodyneLaser.cpp: In member function ‘void gazebo::GazeboRosVelodyneLaser::putLaserData(const gazebo::common::Time&)’:
/home/yufeng/ros_catkin_ws/src/velodyne_simulator/velodyne_gazebo_plugins/src/GazeboRosVelodyneLaser.cpp:234:3: error: ‘math’ has not been declared
  234 |   math::Angle maxAngle = parent_ray_sensor_->AngleMax();
      |   ^~~~
/home/yufeng/ros_catkin_ws/src/velodyne_simulator/velodyne_gazebo_plugins/src/GazeboRosVelodyneLaser.cpp:235:3: error: ‘math’ has not been declared
  235 |   math::Angle minAngle = parent_ray_sensor_->AngleMin();
      |   ^~~~
/home/yufeng/ros_catkin_ws/src/velodyne_simulator/velodyne_gazebo_plugins/src/GazeboRosVelodyneLaser.cpp:248:3: error: ‘math’ has not been declared
  248 |   math::Angle verticalMaxAngle = parent_ray_sensor_->VerticalAngleMax();
      |   ^~~~
/home/yufeng/ros_catkin_ws/src/velodyne_simulator/velodyne_gazebo_plugins/src/GazeboRosVelodyneLaser.cpp:249:3: error: ‘math’ has not been declared
  249 |   math::Angle verticalMinAngle = parent_ray_sensor_->VerticalAngleMin();
      |   ^~~~
/home/yufeng/ros_catkin_ws/src/velodyne_simulator/velodyne_gazebo_plugins/src/GazeboRosVelodyneLaser.cpp:266:18: error: ‘maxAngle’ was not declared in this scope
  266 |   double yDiff = maxAngle.Radian() - minAngle.Radian();
      |                  ^~~~~~~~
/home/yufeng/ros_catkin_ws/src/velodyne_simulator/velodyne_gazebo_plugins/src/GazeboRosVelodyneLaser.cpp:266:38: error: ‘minAngle’ was not declared in this scope
  266 |   double yDiff = maxAngle.Radian() - minAngle.Radian();

According to this github post,it seems that

World::GetSimTime was deprecated in gazebo8 and replaced by World::SimTime.

gazebo math is also removed in gazebo9

seems that code is broken starting with gazebo9. Any plan to fix this issue?