Add "title" filed in ConversationsCanvasesCreateRequest (#1502)

* Add "title" filed in ConversationsCanvasesCreateRequest

* Set ConversationsCanvasesCreateRequest.title

* Remove trailing endline

Author: Lexer11l

slack-api-client/src/main/java/com/slack/api/methods/RequestFormBuilder.java

@@ -1927,6 +1927,7 @@ public static FormBody.Builder toForm(ConversationsRequestSharedInviteListReques
     public static FormBody.Builder toForm(ConversationsCanvasesCreateRequest req) {
         FormBody.Builder form = new FormBody.Builder();
         setIfNotNull("channel_id", req.getChannelId(), form);
+        setIfNotNull("title", req.getTitle(), form);
         if (req.getDocumentContent() != null) {
             setIfNotNull("document_content", GSON.toJson(req.getDocumentContent()), form);
         } else if (req.getMarkdown() != null) {

slack-api-client/src/main/java/com/slack/api/methods/request/conversations/canvases/ConversationsCanvasesCreateRequest.java

@@ -19,6 +19,8 @@ public class ConversationsCanvasesCreateRequest implements SlackApiRequest {
 
     private String channelId;
 
+    private String title;
+
     private String markdown;
     private CanvasDocumentContent documentContent;
-}
+}