ibm watson Discovery.adDocument错误

Question

测试Java API for IBM Watson发现服务

Discovery discovery = new Discovery("2017-09-01"); 

System.out.println("Creating a new document...");
String documentJson = "{\"field\":\"value\"}";
InputStream documentStream = new ByteArrayInputStream(documentJson.getBytes());

AddDocumentOptions.Builder createDocumentBuilder =
        new AddDocumentOptions.Builder(environmentId, collectionId);
createDocumentBuilder.file(documentStream).fileContentType( HttpMediaType.APPLICATION_JSON); 
DocumentAccepted createDocumentResponse = discovery.addDocument(createDocumentBuilder.build()).execute();

应该可以正常工作而不会抛出任何异常。

最后一条语句“discovery.addDocument”抛出异常，错误信息为“当文件不为空时，文件名不能为空”