private @Nullable TopLevelFQNames getScriptTopLevelNames() {
    TopLevelFQNames names = ReadAction.compute(() -> getTopLevelNames());
    if (names == null) return null;

    TopLevelFQNames topLevelFQNames = myTopLevelScriptFQNames;
    StubIndexImpl stubIndex = (StubIndexImpl)StubIndex.getInstance();
    return (topLevelFQNames != null &&
            topLevelFQNames.useful &&
            topLevelFQNames.timestamp == stubIndex.getIndexModificationStamp(GrFullScriptNameStringIndex.KEY, myProject))
           ? topLevelFQNames : null;
  }
private @Nullable TopLevelFQNames getScriptTopLevelNames()