If an item is published to the maven local repository (e.g. using `install` task of Maven plugin) with a non-jar packaging, this is not respected.

It is not respected in so far as that Gradle does not use the packaging name as the extension value for the artifact. Regardless of what the packaging is, Gradle looks for a jar file.

Remote repositories do not have the same behaviour. For a remote repository Gradle will look for an artifact with an extension that matches the packaging element.