The combiner-maven-plugin is designed for those situations where, for whatever reason, the combining of resources is neccessary. The term "resources" is used to indicate that there may be any number of input sources (i.e. disk, socket, etc). Currently, the combiner-maven-plugin only supports resources in the form of files that can be accessed through the filesystem. However, extending the plugin is very easy and thus creating a new input reader for non-filesystem resources would be easy (see below section on customization).
One of the main goals of this project is to ensure quality documentation is produced and maintained. The issue is that having developers write the documentation can easily result in unclear and incomplete documentations as the developers leave out important information that they just know and forget that people outside the project do not know.
If you run into a place where the documentation is unclear or incomplete, please open an issue.