public static void addFile(@NotNull final Collection<? super VirtualFile> result, @Nullable final PsiFile psiFile) {
    if (psiFile != null) {
      ContainerUtil.addIfNotNull(result, psiFile.getVirtualFile());
    }
  }
public static void addFile(@NotNull final Collection<? super VirtualFile> result, @Nullable final PsiFile psiFile)