What class should my XWork action plugin extend?

What class should my XWork action plugin extend?

WebWork actions must implement com.opensymphony.xwork.Action. However, we recommend you make your action extend ConfluenceActionSupport, which provides a number of helper methods and components that are useful when writing an Action that works within Confluence.

Other action base-classes can be found within Confluence, but we recommend you don't use them - the hierarchy of action classes in Confluence is over-complicated, and likely to be simplified in the future in a way that will break your plugins.