private static void detectMoveToDefaultPackage(UsageInfo[] infos,
                                                 MultiMap<PsiElement, @DialogMessage String> conflicts,
                                                 PackageWrapper aPackage) {
    if (!aPackage.getQualifiedName().isEmpty()) return;

    Set<PsiFile> filesWithImports = new HashSet<>();
    for (UsageInfo info : infos) {
      PsiElement element = info.getElement();
      if (element == null) continue;
      PsiReference reference = info.getReference();
      if (reference == null) continue;
      PsiElement target = reference.resolve();
      PsiFile file = element.getContainingFile();
      if (file instanceof PsiJavaFile && target != null && filesWithImports.add(file) && !((PsiJavaFile)file).getPackageName().isEmpty()) {
        conflicts.putValue(element, JavaBundle.message("move.class.import.from.default.package.conflict", RefactoringUIUtil.getDescription(target, false)));
      }
    }
  }
private static void detectMoveToDefaultPackage(UsageInfo[] infos,
                                                 MultiMap<PsiElement, @DialogMessage String> conflicts,
                                                 PackageWrapper aPackage)