This interface is used to define the common methods shared by all "plugin api" classes.
Used internally by EE for registering some caffeinated components, and provided as an easy method for defining classes that plugins can use to register entire components. To be clear, there are certain systems in EE where implementing them for a plugin requires multiple actions and filters being hooked into. Within this class are wrappers for "registering" with a few parameters and then the registry method will take care of setting up all the required filters and hooks for that system to be successfully hooked into.
Direct known implementers
Author: Darren Ethier
Located at core/libraries/plugin_api/EEI_Plugin_API.lib.php