code: @Override
      public void visit(final Child child) {
          final Person person = child.getChild();
          if (child.isSet() && person.isSet()) {
              childList.add(child);
              children.add(person);
          }
      }
docs: Visit a Child. We track this and, if set, the Person who is the
  child.
  
  @see GedObjectVisitor#visit(Child)