display-plugin-updates should optionally show plugins updates for unbound plugins

[kwin]

Currently the goal display-plugin-updates only shows updates for plugins bound in the current project's lifecycle and plugins listed in the effective model in build->plugins->plugin (see https://github.com/mojohaus/versions-maven-plugin/blob/c0589f4a69afc1a53d8f2d461f621339fd0c0710/src/main/java/org/codehaus/mojo/versions/DisplayPluginUpdatesMojo.java#L380).
In some cases one is really interested to see all possible plugin updates, even for the ones which are neither bound (e.g. because the project is of type "pom") nor enabled or ones only listed in some profiles.

A common use case is to check a parent pom for possible plugin updates. That will currently never emit infos for updates of e.g. "maven-jar-plugin" unless that plugin is explicitly mentioned (due to its packaging "pom").

[sultan]

i was thinking about having html reports updates for unbound plugins and transitive dependencies, do you think you could implement your proposal for html too ? maybe one day vulnerabilities would be nice also.

[slawekjaranowski]

can you prepare a simple project which can be added to IT tests.