With this release, Bamboo upgraded its aging WebWork framework to Struts. In many cases, you will not have to adjust your plugin, because we've provided a compatibility layer that will let you compile your source code against both WebWork and Struts. In some cases, however, you may have to modify your code to adjust it to Struts.
If your unit tests access ActionContext, you need to make sure you put calls to BambooTestUtils.createActionContext() and BambooTestUtils.destroyActionContext() in your setUp/tearDown methods.
All compatibility layer classes are marked as deprecated and you are encouraged to switch to the Struts classes. If you need your plugin to stay compatible with older Bamboo versions, keep using the deprecated classes - we are not planning to remove the compatibility layer anytime soon.
In case your plugin is written/upgraded for 5.1, it may be a good idea to replace all occurrences of: