Function writeback_multibody_joint_states 

pub fn writeback_multibody_joint_states(
    context: Query<'_, '_, &RapierContextJoints>,
    multibody_joints: Query<'_, '_, (&RapierContextEntityLink, &RapierMultibodyJointHandle, &mut MultibodyJointState)>,
)

System responsible for writing the state of multibody joints back into the MultibodyJointState component.