anchor.diff:  We also provide real life ruby plugins of interest:
   * The https://github.com/killbill/killbill-cybersource-plugin[Cybersource plugin] is good exmaple to look at to implement a payment plugin (one that implements the https://github.com/killbill/killbill-plugin-api/blob/master/payment/src/main/java/org/killbill/billing/payment/plugin/api/PaymentPluginApi.java[PaymentPluginApi]) and that relies on the https://github.com/activemerchant/active_merchant[Active Merchant gem].
   * The https://github.com/killbill/killbill-avatax-plugin[Avalara plugin] is a good example to look at to implement an invoice plugin (one that implements the https://github.com/killbill/killbill-plugin-api/blob/master/invoice/src/main/java/org/killbill/billing/invoice/plugin/api/InvoicePluginApi.java[InvoicePluginApi]).
  -
  -TODO: Verify the plugin is up to date and works correctly. Should that hello-world depend on `https://github.com/killbill/killbill-plugin-framework-ruby` ?
   
   
   = Deployment
  
positive.code: 
  = Debugging Plugins
  
  
  
negative.code: 
  = Development
  
  It is recommened 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], but depending on the type of plugin to be built there may be better example to look at.
  
  We provide two plugin frameworka that be used to leverage some of the work that plugins need to do:
  * https://github.com/killbill/killbill-plugin-framework-java[`java plugin framework`]
  * https://github.com/killbill/killbill-plugin-framework-ruby[`ruby plugin framework`]
  
  Also, for internal reference you might want to take a look at the https://github.com/killbill/killbill-platform/blob/killbill-platform-0.22/osgi-bundles/libs/killbill/src/main/java/org/killbill/killbill/osgi/libs/killbill/KillbillActivatorBase.java#L59[KillbillActivatorBase], that most plugins inherit and that provide all the abstractions that plugin require (access to java apis, dabadase handle, system properties, logging,...)
  
  == Java Plugins
  
  