ngx-codemirror - Unable to use fold gutter in XML Message

I have an Angular application and I'm using ngx-codemirror to build a codemirror in my respective application. In ngx-codemirror there's an option called foldgutter and I have made it true.

app.component.ts

  public codeMirrorOptions: any = {
    theme: 'material',
    lineNumbers: true,
    lineWrapping: true,
    foldGutter: true,
    gutters: ["CodeMirror-linenumbers", "CodeMirror-foldgutter", "CodeMirror-lint-markers"],
    autoCloseBrackets: true,
    matchBrackets: true
  };

app.component.html

<ngx-codemirror [(ngModel)]="selectedMessageBody"
                                        [options]="codeMirrorOptions">
                        </ngx-codemirror>

By setting up the respective value, I'm able to use fold gutter if the message is JSON but if it's XML the folder gutter option is not visible.

I'm not sure what I'm missing.