Currently the Github pages plugin deletes everything in the gh-pages branch. It would be nice if an optional behavior could be defined in which the plugin only deletes the folders/files defined in the copy spec (or alternatively allow defining a target folder, instead of always using /)

This would solve the following use cases:

• In a multi module project each module can have the plugin applied and can define its own files to be pushed (e.g. each module can push its JavaDoc without deleting everything pushed by other modules)
• You might want to keep already pushed JavaDoc of older releases on the gh-pages branch, e.g.

githubPages {
        repoUri = '...'
        commitMessage "Upload JavaDoc: $project.name/$project.version"
        pages {
            from javadoc.outputs.files
            into "docs/$project.name/$project.version"
        }
    }

• The gh-pages branch might contain a full fledged Jekyll website which grows over time (maybe also contains binary data). In order to keep the master branch small for GIT clones you don't want to have that website stored in src/main/gh-pages (which by default is part of the pages { ... } copy spec)