The document discusses Fluentd's changes to its plugin API between versions 0.12 and 0.14. In 0.14, the API was overhauled to separate entry points from implementations and introduce a plugin base class to control data and control flow. A compatibility layer was added to allow most 0.12 plugins to work unmodified in 0.14 by handling calls to overridden methods. However, plugins that override certa