anchor.diff:  
   The file `plugin_identifiers.json` is used to keep a mapping between the `pluginKey` (the user visible plugin identifer), and the `pluginName` (runtime identifier used by Kill Bill when scanning the filesystem). The next section provides more details about those.
   
  -==== Plugin Coordinates, Plugin Key, Plugin Name, ...
  +=== Plugin Coordinates, Plugin Key, Plugin Name, ...
   
   Today, both our `ruby` and `java` plugins are released through maven and are therefore identified through their maven coordinates. We might support other schemes in the future but today this is the only way we offer to download and install publicly released plugins. Plugin Coordinates are too cumbersome to manipulate though and are unsuitable for non-published plugins (typical use case for a plugin being developed), so we introduced some identifers.
   
  
positive.code: 
  == Development
  
  It is recommended to clone some of our existing plugins to get started. For `java`, the https://github.com/killbill/killbill-hello-world-java-plugin[hello world plugin] is a good starting point. For `ruby`, we also provide a https://github.com/killbill/killbill-hello-world-ruby-plugin[hello world plugin]. Depending on the type of plugin to be built, there may be a better example to look at (e.g. look at an existing payment plugin if you are building a new gateway integration).
  
  We provide two plugin frameworks that can be used to implement some of the work that plugins need to do - although your plugin does not have to rely on these frameworks, it is often a good idea to leverage those to avoid boilerplate code.
  
  
negative.code: Each entry in that repository is identified by a key, and that key is the `pluginKey`.
  * Third party plugins: For third party plugins, the key is specified at the time the plugin gets installed. The key must be of the form `<prefix>::<something>` to make sure there is no name collision with Kill Bill plugin keys.
  
  == Plugin Installation
  
  Kill Bill looks for plugins at the path specified by the `org.killbill.osgi.bundle.install.dir` property in the Kill Bill configuration file. So, installing the plugin simply means placing the plugin artifact at this path. This can either be done manually or via kpm as explained below.
  
  === Deploying by Hand
  
  