gazebo_plugins causing colcon build to fail

[EGAlberts]

I'm trying to port a gazebo plugin made for ROS1 to ROS2 humble for use with Gazebo classic (11).

In the code they use the following header file:

#include <gazebo_plugins/gazebo_ros_utils.h>

Naturally, to resolve this dependency I add
find_package(gazebo_plugins REQUIRED)
(A package which I can confirm is installed within my ROS2)
to the CMakeLists for the package.
However, introducing this as a dependency appears to break the colcon build completely.
I tried for example to create an entirely fresh package. As soon as this dependency is added it breaks.

[EGAlberts]

After a lot of messing around I discovered the following:
I was including this command in my cmakeLists list(APPEND CMAKE_CXX_FLAGS "${GAZEBO_CXX_FLAGS}")
Which was harmless and I picked up in some gazebo tutorial along the way, but triggered errors when I include packages such as gazebo_ros and gazebo_plugins