@TestOnly
  public @NotNull List<VirtualFile> getRoots() {
    if (myEntries.isEmpty()) return Collections.emptyList();
    VirtualFile[] result = new VirtualFile[myEntries.size()];
    for (Object2IntMap.Entry<VirtualFile> entry : myEntries.object2IntEntrySet()) {
      result[entry.getIntValue()] = entry.getKey();
    }
    return Arrays.asList(result);
  }
@TestOnly
  public @NotNull List<VirtualFile> getRoots()