no GetAngles() member in JointState Class in Gazeo Api 9?

edit

error:

 /home/robot/rtt_gazebo/rtt_gazebo_examples/src/default_gazebo_component.cpp:107:41: error: ‘__gnu_cxx::__alloc_traits<std::allocator<gazebo::physics::JointState> >::value_type {aka class gazebo::physics::JointState}’ has no member named ‘GetAngles’
         state_pos_[j] = joint_states[j].GetAngles();

code:

 joint_states[j](JointPtr gazebo_joints_[j]);
        state_pos_[j] = joint_states[j].GetAngles();
  std::vector<gazebo::physics::JointPtr> gazebo_joints_;
  std::vector<gazebo::physics::JointState> joint_states;

i'm using gazebo9 version. as i studied this gazebo 9 api jointstate class, their is presence of getangle member in class jointstate, than why is this error coming.