daz, sterling - thanks for your insights. I think it’s appropriate to let this one go and not to do anything about it.
If I compile the plugin with Gradle 2.8 and then run a build using the plugin with 2.8, then it all works fine. So it’s only when you compile the plugin with 2.4 and then do the build with 2.8 do you have an issue. After adding the toString(), then the build works fine with 2.4 and 2.8.
I think that’s good enough.