You're reading the documentation for a version of ROS 2 that has reached its EOL (end-of-life), and is no longer officially supported. If you want up-to-date information, please have a look at Iron.
The project has received major contributions from the following companies and institutions.
Supported by ROSIN - ROS-Industrial Quality-Assured Robot Software Components. More information: http://rosin-project.eu
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 732287.