A template source is a component that provides templates to the builder. A template source fetches templates from a certain location, in a certain way, that is known by the template source plugin, and unkonown to the javadocbuilder plugin, templates and exposes them to the plugin. The templates have some data associated, like a identifier (which is valid only inside the template source) a descriptive name, a description, suggested output patterns.
Since the javadocbuilder plugin does not know almost anything about templatesouces, they must provide a way to configure themselves to the user. This is usually done in property pages. The javadocbuilder UI plugin contains a property page named template sources, under which different template source implementations shuold hook their pages for configuration.