private @NotNull VirtualFileEnumeration doExtractFileEnumeration() {
    isSearchInModuleContent(myModule); // init myModules
    // todo might be not cheap
    if (myRoots.size() > 1 && (hasOption(MODULES) && myModules.size() > 1 || hasOption(LIBRARIES))) {
      return VirtualFileEnumeration.EMPTY;
    }

    return getFileEnumerationUnderRoots(myRoots.keySet());
  }
private @NotNull VirtualFileEnumeration doExtractFileEnumeration()