@Nullable
  private static PsiDirectory getCommonDirectory(PsiElement[] movedElements) {
    PsiDirectory commonDirectory = null;

    for (PsiElement movedElement : movedElements) {
      final PsiFile containingFile = movedElement.getContainingFile();
      if (containingFile != null) {
        final PsiDirectory containingDirectory = containingFile.getContainingDirectory();
        if (containingDirectory != null) {
          if (commonDirectory == null) {
            commonDirectory = containingDirectory;
          }
          else {
            if (commonDirectory != containingDirectory) {
              return null;
            }
          }
        }
      }
    }
    if (commonDirectory != null) {
      return commonDirectory;
    }
    else {
      return null;
    }
  }
@Nullable
  private static PsiDirectory getCommonDirectory(PsiElement[] movedElements)