Shows how Groovy allows delegating without exposing the encapsulated type

Delegating.groovy

@CompileStatic
class MyString {

    @Delegate
    private final String decorated

    MyString(String decorated) {
        this.decorated = decorated
    }
}

@CompileStatic
class Test {
    static void main(String[] args) {
        def m = new MyString("blah")
        assert m.startsWith("bl")     // compiles, passes
        assert !(m instanceof String) // passes
    }
}