As shown in link [1], groovy supports @Singleton annotation which can be used directly on a class definition. This AST transformation results in creation of the field called "instance" and accessor method called "getInstance()".

Our code completion should take this transformation into account and show both field and method when @Singleton is used.

Example:

@Singleton
class Showcase {
}

Showcase show = new Showcase();
show.^

.. using CC on the ^ location should shown instance field and getInstance() method.

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