There should be way for providing List of Document for analyzeSentiment instead of single Document

I am trying to get the Sentiment for the conversation between Agent and Customer on sentence level using **Google Cloud Natural Language API**.
But observation is, i have to call API for each sentence Is there any way to get the sentiment for List of Document And after Successfull Sentiment i am able to map that sentiment to each sentence.

Here is the snniped code which i tried for sentiment analysis

There is no way to give List of Document

```java
Document doc = Document.newBuilder()
.setContent(TEXT)
.setType(Document.Type.PLAIN_TEXT)
.build();
AnalyzeSentimentResponse response = languageServiceClient.analyzeSentiment(doc);
Sentiment documentSentiment = response.getDocumentSentiment();
log.info("sentence:{}", fromObjectToJson(documentSentiment));
```

Start with the Java analyzeSentiment call shown in the issue and review the Google Cloud Natural Language API's document and sentiment-analysis interfaces. Determine whether list-based analysis is supported and what response structure would allow sentiments to be mapped back to sentences; the issue is done when the supported approach or required API change is clearly established.

索引モデルが issue の本文から書いたものです。