code: public <T> T getDocumentSource(String path,Class<T> beanType) throws ElasticSearchException{
  		try {
  			T searchResult = (T) this.client.executeRequest(path,null,   new GetDocumentSourceResponseHandler( beanType),ClientUtil.HTTP_GET);
  			return searchResult;
  		}
  		catch(ElasticSearchException e){
  			return ResultUtil.hand404HttpRuntimeException(e,beanType,ResultUtil.OPERTYPE_getDocument);
  		}
  	}
docs: 获取文档Source对象，不带索引元数据
  https://www.elastic.co/guide/en/elasticsearch/reference/current/docs-get.html
  @param path twitter/_doc/1/_source 其中1为文档id
  @return
  @throws ElasticSearchException