Using Groovy traits with @DeleGate AST transform

GroovyDelegatingTrait

// has all methods of List
trait ListLike {
    @Delegate List linkedList = new LinkedList()
}

// stores anything but exposes only Strings
class StringList implements ListLike {
    String get(int index) { linkedList.get(index).toString() }
}

ListLike stringList = new StringList()

stringList << 0                // adding an int
assert '0' == stringList[0]    // getting a String

See Compatibility with AST transformations it says "Traits are not officially compatible with AST transformations".