Remove empty on_shutdown() callbacks (ros-controls#1477)

Author: Juliaj

diff_drive_controller/include/diff_drive_controller/diff_drive_controller.hpp

@@ -72,9 +72,6 @@ class DiffDriveController : public controller_interface::ControllerInterface
   controller_interface::CallbackReturn on_error(
     const rclcpp_lifecycle::State & previous_state) override;
 
-  controller_interface::CallbackReturn on_shutdown(
-    const rclcpp_lifecycle::State & previous_state) override;
-
 protected:
   struct WheelHandle
   {

diff_drive_controller/src/diff_drive_controller.cpp

@@ -578,12 +578,6 @@ bool DiffDriveController::reset()
   return true;
 }
 
-controller_interface::CallbackReturn DiffDriveController::on_shutdown(
-  const rclcpp_lifecycle::State &)
-{
-  return controller_interface::CallbackReturn::SUCCESS;
-}
-
 void DiffDriveController::halt()
 {
   const auto halt_wheels = [](auto & wheel_handles)

joint_trajectory_controller/include/joint_trajectory_controller/joint_trajectory_controller.hpp

@@ -84,9 +84,6 @@ class JointTrajectoryController : public controller_interface::ControllerInterfa
   controller_interface::CallbackReturn on_error(
     const rclcpp_lifecycle::State & previous_state) override;
 
-  controller_interface::CallbackReturn on_shutdown(
-    const rclcpp_lifecycle::State & previous_state) override;
-
 protected:
   // To reduce number of variables and to make the code shorter the interfaces are ordered in types
   // as the following constants

joint_trajectory_controller/src/joint_trajectory_controller.cpp

@@ -1077,14 +1077,6 @@ bool JointTrajectoryController::reset()
   return true;
 }
 
-controller_interface::CallbackReturn JointTrajectoryController::on_shutdown(
-  const rclcpp_lifecycle::State &)
-{
-  // TODO(karsten1987): what to do?
-
-  return CallbackReturn::SUCCESS;
-}
-
 void JointTrajectoryController::publish_state(
   const rclcpp::Time & time, const JointTrajectoryPoint & desired_state,
   const JointTrajectoryPoint & current_state, const JointTrajectoryPoint & state_error)

tricycle_controller/include/tricycle_controller/tricycle_controller.hpp

@@ -76,8 +76,6 @@ class TricycleController : public controller_interface::ControllerInterface
 
   CallbackReturn on_error(const rclcpp_lifecycle::State & previous_state) override;
 
-  CallbackReturn on_shutdown(const rclcpp_lifecycle::State & previous_state) override;
-
 protected:
   struct TractionHandle
   {

tricycle_controller/src/tricycle_controller.cpp

@@ -440,11 +440,6 @@ bool TricycleController::reset()
   return true;
 }
 
-CallbackReturn TricycleController::on_shutdown(const rclcpp_lifecycle::State &)
-{
-  return CallbackReturn::SUCCESS;
-}
-
 void TricycleController::halt()
 {
   traction_joint_[0].velocity_command.get().set_value(0.0);