Message about archiveVersion seems misleading or incomplete...?

You should be able to put the version outside the “jar” section, something like:

version = '0.0.1'
group = 'org.foo'

jar {
    manifest {
        attributes 'Implementation-Title': 'Foo', 'Implementation-Version': archiveVersion
    }
}

The jar task by default sets archiveVersion = project.version (‘0.0.1’)
The publishing section should do the same, i.e. taking the version from project.version unless you override it.