MOVEIT robot_state; current velocities and accelerations/effort

i need the updated robot state (including velocities and accelerations/efforts) of my 6dof arm in moveit. when i query the current robot state using getCurrentState() of the moveit::planning_interface::MoveGroup class, i get a robot state that contains the current joint positions (they update when i execute plans on my arm in simulations and in real as expected). However, the joint velocities and accelerations/efforts contain an empty array; [ ]. I tried to call startStateMonitor() befor querying the robot state but velocities/accelerations or efforts are still empty. a work around would be to subscribe to the /joint_states topic and update the current robot state "manually" using setVariableValues() of the moveit::core::RobotState class that takes directly a JointState message. the reason i'm looking into this is that i need a robot state with at least the joint positions to use the moveit api to compute the jacobian of my arm. further i need the current velocities to map cartesian velocities from a joystick to joint velocites. as i said, i could just subscribe to joint_velocities but i'd like moveit to update the robot state on its own. am i missing something or is it really necessary to update the robot state "manually" to get the current velocities and accelerations/efforts? Thanks in advance, Pascal