Link to iuser
The IUser interface is used internally to combine different userTypes, like the minecraft console, a normal user and command blocks in one type.
You will probably seldomly need this.
Importing the package
Link to importing-the-package
It might be required for you to import the package if you encounter any issues (like casting an Array), so better be safe than sorry and add the import.
Link to extending-icommandsender
Link to methods
Currently there are no distinct functions for IUser objects.