Consider the following:

package foo;
public class Bar {
  Object packagePrivate;
}

package foo;
public class Baz extends Bar {
}

def pojo = new foo.Baz()
pojo.packagePrivate

Since C and D are in the same package, Groovy (since 2.4) propagates the field to the meta-info index of D. Therefore, a class/script from another package can access "field". However, highlighting is shoring as unknown (underlined).