public Object[] choices<actionName>([<parameter type> param]...)
Complements an action method.
The choices method provides a set of options for each parameter of an action. This method is
called when the user inferface prompts for all the parameters from the user, so the options cannot
depend on the state of any of the other parameters. Note - this does not limit the state of the
parameter, see the validate methods for a way to do that.
For each parameter the array should contain either null, an array, or a collection.