Update Maven plugin management to expose a configuration property for the Native Metadata Repository version

As discussed with @odrotbohm, overriding the version of the metadata repository requires to redefine the plugin coordinates. There’s an interest that Spring Boot has an opinion about this. The NBT plugin hardcodes the version to use and it can lag with an older version of the plugin.

At the moment the version offered is 0.1.0 while 0.1.2 is available.

[snicoll]

Because the default value would need to be defined in both the Maven parent POM and as some value within our Gradle plugin?

The plugin sets a version by default and we don’t want to override it. If a user applies version X.Y.Z of the plugin, they should get a certain version of the metadata OOTB and upgrading the plugin should upgrading the version of the metadata if they haven’t expressed an opinion. This makes the whole thing confusing if we expose a property. In retrospect, it’s not even related to Gradle at all as overriding the version of the plugin in Maven should give you that as well.

[wilkinsona]

Things would get complicated for users if they overrode the version of the NBT plugin. They’d then get a default version of the metadata that’s unexpected.

Taking a small step back from the metadata version, I’m not even sure that we should be managing the version of the NBT plugin. We don’t do so for Gradle and doing so for Maven may create more problems than it solves.

Both the NBT plugin and the metadata are evolving quite rapidly at the moment. If we manage the version in Boot, there becomes an expectation that the version will only be updated in line with our usual maintenance policy – we’d only pick up maintenance releases of the metadata and the build plugin in maintenance releases of Boot. I’m not sure that the build plugin is ready for that, even less so the metadata. We may be better avoiding this problem by not managing the versions at all but this will come at the code of making application poms more verbose. It’s unfortunate that Maven doesn’t allow us to provide some default configuration for a plugin without having to specify a version.