code: @BetaApi(
        "The surface for long-running operations is not stable yet and may change in the future.")
    public final OperationFuture<Document, KnowledgeOperationMetadata> createDocumentAsync(
        String parent, Document document) {
  
      CreateDocumentRequest request =
          CreateDocumentRequest.newBuilder().setParent(parent).setDocument(document).build();
      return createDocumentAsync(request);
    }
docs: Creates a new document.
  
  <p>Operation &lt;response: [Document][google.cloud.dialogflow.v2beta1.Document], metadata:
  [KnowledgeOperationMetadata][google.cloud.dialogflow.v2beta1.KnowledgeOperationMetadata]&gt;
  
  <p>Sample code:
  
  <pre><code>
  try (DocumentsClient documentsClient = DocumentsClient.create()) {
  KnowledgeBaseName parent = KnowledgeBaseName.of("[PROJECT]", "[KNOWLEDGE_BASE]");
  Document document = Document.newBuilder().build();
  Document response = documentsClient.createDocumentAsync(parent.toString(), document).get();
  }
  </code></pre>
  
  @param parent Required. The knoweldge base to create a document for. Format:
  `projects/&lt;Project ID&gt;/knowledgeBases/&lt;Knowledge Base ID&gt;`.
  @param document Required. The document to create.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails