text: About ROS 2 middleware implementations — ROS 2 Documentation: Galactic documentation
  The <implementation_name>_cmake_module package contains any CMake Modules and functions needed to find the supporting dependencies for the middleware implementation. For example, rti_connext_dds_cmake_module provides wrapper logic around the CMake Module shipped with RTI Connext DDS to make sure that all packages that depend on it will select the same installation of RTI Connext DDS. Similarly, fastrtps_cmake_module includes a CMake Module to find eProsima's Fast DDS and gurumdds_cmake_module includes a CMake Module to find GurumNetworks GurumDDS. Not all implementations will have a package like this: for example, Eclipe's Cyclone DDS already provides a CMake Module which is used directly by its RMW implementation without the need of additional wrappers.