anchor.diff:  
   The next stage is to identify existing (similar) plugins which could be used as a starting point to write the code. At this point, this becomes a normal software development cycle, including writing unit tests for that plugin (independent of Kill Bill).
   
  -TODO: Provide detailed instructions based on the hello-world plugin (email from Guisepe). Need to fix hello-workd first.
  -
  -
   = Development
   
   
  
positive.code: 
  == Java Plugins
  
  TODO: 
  
  == Ruby Plugins
  
  
negative.code: 
  * They have access to the database so as to maintain their own state. However they **should not interract with the Kill Bill core tables directly** but rely on apis to retrieve and change,
  * They have access to system properties
  * They have the ability to export their own endpoints under a `/plugins/<pluginName>` (see https://github.com/killbill/killbill-hello-world-java-plugin/blob/master/src/main/java/org/killbill/billing/plugin/helloworld/HelloWorldActivator.java#L37[Hello World plugin]
  * They receive all the events in the system
  * They are isolated from the rest of the code and can use their own library (versions) without risk of conflict
  
  