Backport PR #11370: Make orig_nbformat optional #11005 (#11384)

Co-authored-by: Frédéric Collonval <fcollonval@users.noreply.github.com>

galata/src/galata.ts

@@ -292,8 +292,7 @@ export namespace galata {
             nbconvert_exporter: 'python',
             pygments_lexer: 'ipython3',
             version: '3.8.0'
-          },
-          orig_nbformat: 4
+          }
         },
         nbformat: 4,
         nbformat_minor: 4

packages/nbformat/src/index.ts

@@ -46,7 +46,7 @@ export interface ILanguageInfoMetadata extends PartialJSONObject {
 export interface INotebookMetadata extends PartialJSONObject {
   kernelspec?: IKernelspecMetadata;
   language_info?: ILanguageInfoMetadata;
-  orig_nbformat: number;
+  orig_nbformat?: number;
 }
 
 /**

packages/shared-models/src/ymodels.ts

@@ -331,7 +331,7 @@ export class YNotebook
    */
   getMetadata(): nbformat.INotebookMetadata {
     const meta = this.ymeta.get('metadata');
-    return meta ? deepCopy(meta) : { orig_nbformat: 4 };
+    return meta ? deepCopy(meta) : {};
   }
 
   /**