private static @NotNull Collection<PsiFile> findFxmlWithController(@Nullable NestedControllerCandidate nestedControllerCandidate) {
    if (nestedControllerCandidate != null) {
      final String qualifiedName = nestedControllerCandidate.controllerClass.getQualifiedName();
      if (qualifiedName != null) {
        final Project project = nestedControllerCandidate.controllerClass.getProject();
        return JavaFxControllerClassIndex.findFxmlWithController(project, qualifiedName);
      }
    }
    return Collections.emptyList();
  }
private static @NotNull Collection<PsiFile> findFxmlWithController(@Nullable NestedControllerCandidate nestedControllerCandidate)