Marker file is not generated

[YasuChiba]

Hi,
Thank you for maintaining ros2java!

In my understanding, current build tools related to the ros2java project don't generate the marker file described in this document.

Even if AMENT_PREFIX_PATH is provided by colcon-ros-gradle (#7), we need to create a marker file as well because the ros2 command cannot find the package without the marker file.
There seems to be a discussion about which project should implement this feature in ros2-java/ament_java#9
But I still not get which project should implement this.
So, as a temporary thing, I've implemented it in this project.
YasuChiba@e299e25

I'll send out a PR. Can anyone check it out?

(I'm new to gradle/ament/colcon. I'm sorry if my understanding is wrong)

[jacobperron]

Yes, we are missing logic to install a marker file. I think we also should install the package.xml too. IMO, the gradle projects themselves should be responsible for this, perhaps through a plugin like ament_gradle_plugin or some helper library, but I don't think it hurts if colcon-ros-gradle does this too.

Even better, would be if colcon could detect if the marker and package.xml were not being installed by the gradle project and emit a warning. This is what we do for ament_python packages, for example.

[jacobperron]

Resolved by #11