Error in @TypeChecked when method in both Interface and Superclass

import groovy.transform.TypeChecked

interface Ifc
{
  Object getProperty(String s)
}

class DuplicateMethodInIfc implements Ifc  // implemented in groovy.lang.GroovyObject
{
}

@TypeChecked
class Tester
{
  DuplicateMethodInIfc dup = new DuplicateMethodInIfc()
  Object obj = dup.getProperty("foo")   // <== Error here
}