anchor.diff:  
   . Open plugin `pom.xml`
   
  -. Specify the following in the `properties` section of the `pom.xml`:
  +. Specify the following in the `properties` section of the `pom.xml` (Replace `<package>` with the fully qualified name of the package that you would like to export):
   [source,xml]
    <osgi.extra-import>
               <package1>;
  
positive.code: * Packages specified in the `killbill-oss-parent` pom file.
  
  
  ==== Packages exported by Kill Bill
  
  The Kill Bill system bundle also exports the packages which it desires to share with plugins. The packages exported by the Kill Bill system bundle are specified in the https://github.com/killbill/killbill-platform/blob/4e735e9c3367cee2272964f16d028795f55592d3/osgi/src/main/java/org/killbill/billing/osgi/config/OSGIConfig.java#L49[OSGIConfig.java]. Additionally, Kill Bill also offers a system property, `org.killbill.osgi.system.bundle.export.packages.extra`, to specify additional packages to be exported by the system bundle and that could in turn be imported by a plugin.
  
  ==== Importing Additional Packages in Plugins
  
  Sometimes, a plugin may require to use some additional packages from Kill Bill (other than those automatically imported as specified above). In such cases, you will need to explicitly *export* the package from Kill Bill and *import* it in the plugin as explained below.
  
negative.code: </osgi.extra-import> 
  
  This causes the package to be added to the `Import-Package` header of the plugin jar. You can see an example of this in the https://github.com/killbill/killbill-adyen-plugin/blob/0c5205d2ee42b543852e7cbd1a6f6f065ad575e5/pom.xml#L44[Kill Bill Adyen Plugin pom file]. 
  
  ==== Exporting Additional Packages from a Plugin
  
  A plugin can also export packages corresponding to the classes that it wants to share with other plugins. This mechanism is particularly useful since it allows plugins to share custom functionality with other plugins. 
  
  To *export* a package from a plugin, you need to follow the steps given below.
  
  . Open plugin `pom.xml`.
  
  . Specify the following in the `properties` section of the `pom.xml` (Replace `<package>` with the fully qualified name of the package that you would like to export): 
  [source,xml]
  <osgi.export>
    <package1>,
    <package2>
     ....
    <packagen>
  </osgi.export>
  
  . This causes the specified packages to be added to the `Export-Package` header of the plugin jar.
  
  . Other plugins can then use the classes in these packages by importing them as explained above.
  
  === Examples of Plugins
  
  