can not get correct subtitle text according to parameters by calling getDialogue

[xkening]

I find that subtitle text returned frome getDialogue(0,1,1) does not have speaker names.

`inline std::string SubtitleItem::getDialogue(bool keepHTML, bool doNotIgnoreNonDialogues, bool doNotRemoveSpeakerNames)
{
if(_justDialogue.empty())
extractInfo(keepHTML, doNotIgnoreNonDialogues, doNotRemoveSpeakerNames);

return _justDialogue;

}`

why check empty in this function?