As shown in link [1], groovy supports @Delegate annotation which can be used within a class definition on a specific field. It results in delegating all method calls on declaring class to that specified field.

Our code completion should take this transformation into account and show all methods of each @Delegate field.

Example:

interface Whatever {
    void showMe();
}

class Implementor {
    @Delegate Whatever w
    void normal();
}

Implementor abc = new Implementor();
abc.^

.. using CC on the ^ location should shown showMe() method together with it's own methods.

[1] http://groovy.codehaus.org/Delegate+transformation