[Handle] Use get_optional instead of get_value<double>

[saikishor]

After some discussion with @christophfroehlich we thought get_optional might make more sense and explicit compared to get_value<double> and again get its value with .value()

[codecov]

Codecov Report

Attention: Patch coverage is 89.67742% with 16 lines in your changes missing coverage. Please review.

Project coverage is 89.35%. Comparing base (d126642) to head (8ef56f2).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
...terface/include/semantic_components/gps_sensor.hpp	55.17%	5 Missing and 8 partials ⚠️
...nclude/semantic_components/force_torque_sensor.hpp	95.23%	0 Missing and 1 partial ⚠️
...terface/include/semantic_components/imu_sensor.hpp	95.45%	0 Missing and 1 partial ⚠️
...erface/include/semantic_components/pose_sensor.hpp	94.11%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2061      +/-   ##
==========================================
- Coverage   89.40%   89.35%   -0.06%     
==========================================
  Files         139      139              
  Lines       14975    14978       +3     
  Branches     1281     1287       +6     
==========================================
- Hits        13389    13383       -6     
+ Misses       1107     1105       -2     
- Partials      479      490      +11     

Flag	Coverage Δ
unittests	89.35% <89.67%> (-0.06%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...mantic_components/semantic_component_interface.hpp	90.90% <100.00%> (ø)
...rface/test/test_chainable_controller_interface.cpp	100.00% <ø> (ø)
...chainable_controller/test_chainable_controller.cpp	88.23% <100.00%> (-0.14%)	⬇️
...r_manager/test/test_controller/test_controller.cpp	88.73% <100.00%> (ø)
...t_controllers_chaining_with_controller_manager.cpp	99.25% <100.00%> (ø)
...re_interface/include/hardware_interface/handle.hpp	81.81% <100.00%> (+1.29%)	⬆️
...de/hardware_interface/loaned_command_interface.hpp	60.00% <100.00%> (+7.50%)	⬆️
...lude/hardware_interface/loaned_state_interface.hpp	60.00% <100.00%> (ø)
...rface/test/mock_components/test_generic_system.cpp	99.72% <ø> (ø)
...dware_interface/test/test_component_interfaces.cpp	97.63% <100.00%> (-0.06%)	⬇️
... and 8 more

... and 3 files with indirect coverage changes

[christophfroehlich]

I like.

If we don't merge this, we should apply the changes from f958dfe also to the master.

[Juliaj]

@saikishor @christophfroehlich , just for my knowledge, could you provide some context and outline a few discussion points ? 🙇

[christophfroehlich]

see #2055 and #1976, we were not really happy with the API but hadn't a better idea.

[christophfroehlich]

and here the origin of the API discussions
ros-controls/ros2_controllers#1442
ros-controls/ros2_controllers#1467
ros-controls/ros2_controllers#1443

[christophfroehlich]

basically,
get().get_optional().value() instead of get().get_value<double>().value() in controller and hardware components 😉