code: @Nullable static VariableElement findCreator(
        Elements elements, Types types, TypeElement subject) {
  
      TypeMirror creatorType = types.getDeclaredType(
          elements.getTypeElement(PARCELABLE_CREATOR_CLASS_NAME),
          types.getWildcardType(null, null));
  
      List<? extends Element> members = elements.getAllMembers(subject);
      for (VariableElement field : ElementFilter.fieldsIn(members)) {
        if (field.getSimpleName().contentEquals("CREATOR")
            && types.isAssignable(field.asType(), creatorType)
            && field.getModifiers().contains(Modifier.STATIC)
            && field.getModifiers().contains(Modifier.PUBLIC)) {
          return field;
        }
      }
  
      return null;
    }
docs: If {@code subject} has a {@code Parcelable.Creator} field instance, return it.