This event indicates that the server has detected the end of the user's speech utterance and expects no additional speech. Therefore, the server will not process additional audio (although it may subsequently return additional results). When the client receives 'END_OF_SINGLE_UTTERANCE' event, the client should stop sending the requests. However, clients should keep receiving remaining responses until the stream is terminated. To construct the complete sentence in a streaming way, one should override (if 'is_final' of previous response is false), or append (if 'is_final' of previous response is true). This event is only sent if `single_utterance` was set to `true`, and is not used otherwise.
