private static @Nullable PsiField getNestedControllerField(@NotNull XmlAttributeValue fxIdValueElement) {
    final String fxId = fxIdValueElement.getValue();
    if (!StringUtil.isEmpty(fxId)) {
      final XmlTag tag = PsiTreeUtil.getParentOfType(fxIdValueElement, XmlTag.class);
      if (tag != null && FxmlConstants.FX_INCLUDE.equals(tag.getName())) {
        final PsiClass controllerClass = JavaFxPsiUtil.getControllerClass(tag.getContainingFile());
        if (controllerClass != null) {
          return controllerClass.findFieldByName(fxId + FxmlConstants.CONTROLLER_SUFFIX, true);
        }
      }
    }
    return null;
  }
private static @Nullable PsiField getNestedControllerField(@NotNull XmlAttributeValue fxIdValueElement)